More this week on vinyl floors being discolored by rubber-backed rugs.

I really didn't know how widespread the problem was when I first wrote about it because I don't have vinyl flooring, but it is indeed a problem.

Lowe's employee Jerry McHale from West Lancaster said he had the same situation occur in his house, only the floor turned a deep purple, and it could not be cleaned. McHale and his wife had placed a rubber-backed floor mat inside the French door in their kitchen that led to the deck. Over time, the spot under the mat had turned ink-purple.

"We tried numerous cleaning products, to no avail," he said.

McHale sought help from the flooring department at the Lancaster Lowe's as well as from employees at Armstrong Industries World Headquarters, who work less than a mile from the store.

"Believe it or not, heat is the main reason for the discoloration," McHale said he learned. "Apparently, heat from the direct sunlight through the French door gets trapped under the floor mat and causes the chemical reaction, which discolors the vinyl floor.

Therefore, it is not recommended to use a rubber-backed floor mat in an area on a vinyl floor that receives direct sunlight.

"We have since replaced the vinyl with a wood laminate and have had no problems," he said.

Bob Zyko of the Higganum section of Haddam, Conn., said he was aware of the problem of yellow-floor staining because of his background working with neoprene-coated belting products.

"When coated belting projects were stacked on the vinyl lab flooring for a period of time, they yellowed the floor - permanently," he said.

Zyko assumed that rug and mat manufacturers would use nonstaining materials for their rubber backings.

"So we now have some yellowed vinyl floors," he said.

How can you tell which carpet backings are nonstaining? He asked the questions since the carpet labels do not provide much information, and he has yet to see one that claims to be nonstaining.

You should look for a nonstaining vinyl-backed mat or a woven rug that is colorfast. Most of these products are identified as "colorfast" by the manufacturer. Armstrong cautions against using rubber-backed mats and rugs because the company is aware of the chemical reaction that creates the stain.

As I said in the previous column, you cannot remove the stain unless you remove the floor. If you don't want to do it, you'll need to buy a larger rug to hide it.

Whine, whine, whine. Angie's List has compiled a list of which contractors/professionals receive the most complaints.

From one to 10, home-warranty companies; property-management firms; Internet-service providers; cable and satellite providers; wedding professionals (bridal and tuxedo shops, planners); dry cleaners; phone services; auto sales; car services (limos and taxi services); and florists.

Please feel free to e-mail me your own lists. I'll be happy to run them. Keep them clean.

Question: What's the best method for cleaning a toaster oven and its glass? Can I use regular oven cleaner?

Answer: I had hoped to pose this question to staffers here, but when I checked out the toaster oven in the kitchen, it was still encrusted with provolone from a 1983 meltdown.

First, you get rid of the crumbs. Then you wash the tray, the interior, and the shelving with warm, soapy water, since the warm water will melt the grease.

Dry with a lint-free cloth.

Poison control. From the California Poison Control System:

Solvents in cans of snow sprays can be harmful when inhaled. Once the snow spray is dry, it is not dangerous. If eaten, the needles from Christmas trees can cause choking if a needle gets stuck in the throat like a fishbone. Needles falling from a dry tree can be a problem to small children and pets. Eating holly or mistletoe berries can cause nausea, vomiting, and diarrhea. If enough is ingested, more severe symptoms can occur.

Questions? E-mail Alan J. Heavens at aheavens@phillynews.com or write him at The Inquirer, Box 8263, Philadelphia 19101. Volume prohibits individual replies. He is the author of "Remodeling on the Money" (Kaplan Publishing).

Twitter: @alheavens