8 Home Decor “Facts” That Don’t Survive a Source Check

Some decorating advice gets repeated so often that nobody checks it anymore. Plants clean the air, gravel helps drainage, blue walls calm you down. I went back to the original sources behind eight of these: the NASA report, the lab test, the manufacturer’s spec sheet, the university study. Most of them don’t say what the internet says they say.

The Eight Myths at a Glance

1. “Houseplants Purify the Air”

This one traces back to a 1989 NASA report that tested single plants in sealed Plexiglas chambers under one cubic meter in size. The plants did remove chemicals there. In a real room, where air is constantly replaced, the picture changes completely: a 2019 Drexel University review of 12 studies found the median plant cleans about 0.023 m³ of air per hour, and matching a typical building’s ventilation would take “10–1000 plants/m2 of a building’s floor space.”

What to do instead: cut pollution at the source, open a window and use a filter if you need one. Pick plants for light and pet safety. The full breakdown, with a calculator for your own room, is in Do Houseplants Really Clean the Air?

2. “Egg Cartons Soundproof a Room”

In a 2023 test at Riverbank Acoustical Laboratories, 216 egg cartons scored an NRC of 0.50 to 0.80 depending on how they were laid, so they do absorb echo at mid and high frequencies. They did almost nothing for bass, and the lab never tested whether they block sound through a wall, because they can’t: blocking takes mass, and a wall of cartons weighs about 0.38 lb per square foot against 1.6 for one sheet of drywall. They’re also paper on your wall.

What to do instead: seal the gap under the door and around windows to block noise, and use a rug and curtains to cut echo. More in Egg Cartons Do Absorb Sound. They Just Can’t Soundproof Anything.

3. “Put Gravel at the Bottom of the Pot for Drainage”

It sounds logical: coarse stones let water run out faster. Soil doesn’t work that way. As Ed Perry, emeritus horticulture advisor with University of California Cooperative Extension, explains, “gravitational water will not move from a fine textured soil into a coarser soil until the finer soil is saturated.” The gravel doesn’t pull water down. The soil above it stays wet until it can’t hold any more, and the wet zone sits higher in the pot, closer to the roots.

He adds that “the coarser the underlying material, the more difficult it is for water to move across the interface.” So bigger rocks make it worse, not better.

Source check: “gravel improves drainage”

What the internet says: add an inch or two of gravel, pebbles or broken pot shards before the soil so roots don’t sit in water.

What the source actually says: UC Cooperative Extension says the opposite happens, and gives the fix in one line: “fill the container from bottom to top with a well-drained potting soil, and don’t block the drain hole.”

What I’d do: skip the gravel, use a pot with a drain hole, and empty the saucer after watering. If you love a pot without a hole, use it as a cover: keep the plant in a plastic nursery pot inside it and lift it out to water.

4. “Never Use Matte Paint in a Bathroom”

This made sense when flat paints didn’t stand up to steam and scrubbing. It’s no longer a rule. Benjamin Moore sells Aura Bath & Spa as “our premium, matte finish bathroom paint offering unparalleled beauty in high humidity environments,” and lists among its features that it “provides a mildew resistant coating.”

What to do instead: if you want a soft, chalky look in the bathroom, choose a matte that’s made for bathrooms, not a regular flat wall paint, and run the fan during and after showers. Color ideas are in Calming Bathroom Paint Colors.

5. “Blue Walls Will Make You Calmer”

The best real-world test I’ve found is a 2018 study in Frontiers in Psychology by Marco Costa and colleagues. They surveyed 443 students living in six identical university residence buildings in Pisa that differed only in interior color. The effect of the wall color on overall mood wasn’t significant. Blue was the most liked color, chosen by 34.7%, and the abstract reports that “a significant relation was found between a calm mood and preference for blue.” In other words, it’s about liking the color, not the color doing something to you.

What to do instead: paint the color you actually enjoy living with, and get the light right. A calm room is mostly warm lamps in the evening and less clutter, whatever the walls are. See Best Bedroom Paint Colors for Sleep.

6. “Low-Maintenance Houseplants Are Fine on the Balcony”

A snake plant survives neglect indoors, so it should survive a balcony, right? Only in warm weather. NC State Extension’s Plant Toolbox lists snake plant for USDA hardiness zones 10a through 12b, and notes it “tolerates low humidity and cool temperatures around 50 degrees.” Most of the continental US gets far colder than that in winter.

What to do instead: treat tropical houseplants as summer guests on the balcony and bring them in before nights get cold. For year-round balcony planting, choose plants rated for your zone. See Minimalist Balcony Design.

7. “More Watts Means a Brighter Bulb”

That was roughly true when every bulb was incandescent. With LEDs it’s misleading. The FTC is clear: “Lumens measure brightness,” while “wattage only tells you how much energy a bulb uses — not how bright it is.” For reference, “a traditional 60-watt incandescent bulb produces about 800 lumens of light.”

What to do instead: shop by lumens for brightness and by color temperature for mood. Both numbers, plus the third one nobody explains, are in A Bulb Has Three Numbers. Most Guides Explain One.

8. “Candles Last Three Times Longer on a Warmer”

Half true. A warmer melts the wax without burning it, so the jar stays full much longer. The fragrance oils still evaporate, though, and the scent fades well before the wax is gone. You end up with a full jar that doesn’t smell like much.

What to do instead: judge a warmed candle by its smell, not by how full the jar looks, and use a warmer with a timer. The sources and safety numbers are in Candle Warmers vs Burning.

Quick quiz

Myth or fact?

Five statements. Some are true, so don’t just click “myth” on everything.

When Following the Old Advice Is Fine

• Your plants make you happy: keep them. The only problem is buying them to fix your air instead of opening a window.
• Your bathroom has no fan and no window: a semi-gloss or satin is still the safer, easier-to-clean choice there, even with matte bathroom paints on the market.
• You simply love blue: paint it blue. Liking the color is the part that seems to matter.
• A heavy pot keeps blowing over on the balcony: rocks in the bottom add weight, which is a real reason. Just don’t expect them to help drainage.

Questions People Ask

Should you put rocks at the bottom of a plant pot?

Not for drainage. According to UC Cooperative Extension, water won’t move from fine soil into coarse gravel until the soil is saturated, so gravel keeps the soil above it wetter. Fill the pot with potting mix all the way down and keep the drain hole open. The only good reason for rocks is extra weight in a top-heavy pot.

Can you use matte paint in a bathroom?

Yes, if it’s made for bathrooms. Some matte paints are formulated for high humidity and mildew resistance, such as Benjamin Moore’s Aura Bath & Spa. A regular flat wall paint is still a poor choice for a steamy bathroom.

Does wall color affect your mood?

Less than paint marketing suggests. In a study of 443 students living in identical buildings painted different colors, the wall color had no significant effect on overall mood. Preferring blue was linked to a calmer mood, which points to personal taste more than the color itself.

How do I check a home tip myself?

Look for the original source the tip claims, not another article repeating it. University extension pages (look for .edu), manufacturer spec sheets and government pages like the EPA or FTC are usually the most reliable. If a tip cites NASA or “a study” without a link, that’s your cue to look it up.

The Bottom Line

Most home myths start with something real, a NASA chamber test, an old paint formula, a bulb from 1995, and lose the context along the way. The fixes are usually simpler than the myth: open a window, seal a gap, fill the pot with potting mix, read the lumens. And the things the myths were supposed to justify, the plants, the blue walls, the candles, are still worth having for their own sake.

Last checked October 30, 2026: the gravel quotes on the UC Cooperative Extension page, the Aura Bath & Spa product page, the Costa et al. abstract, the NC State snake plant zones and the FTC lumens page. The plant and egg carton figures were checked the same day for their full articles, linked above.

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