Dear Paula: I would like to know which lip color makes teeth look whiter or at least less yellow? I have heard multiple, contradictory answers about blue-based (cool) tones being better than yellow-based (warm) tones and vice-versa. Since everyone is putting so much effort into trying to whiten their teeth, which lipstick enhances the white effect? – Judi, New York City

A: It actually depends more on the actual discoloration of your teeth and the actual color of the lipstick and how it looks on your lip color. In essence that means you need to try on varying shades and see what works.

The general rule you’ve probably heard is that yellow tones don’t contrast with and downplay the yellow of your teeth while blue-tone lipsticks would (making the yellow look more yellow). But rather than playing this game (which doesn’t camouflage much, even if you find the right match), consider talking to your dentist about a teeth whitening treatment or using one of the new over the counter skin whitening treatments, these work brilliantly and then most any lipstick will make your lips and teeth look beautiful.

Dear Paula: I need to know how I can condition my eye lashes and get them to grow fuller and thicker. Just as with the mascara that I apply daily, I would like my lashes to be full and thick again without the application of mascara. Is there anything I could use? I was told once from a beauty consultant at Essence magazine to use mineral oil on my eyelashes at night. Can you confirm this? – Sherry, via email

A: The product you are looking for doesn’t exist. If it was possible to grow thicker, fuller lashes, there wouldn’t be hundreds of mascaras being sold with new ones launched every month. Not only doesn’t mineral oil help eye lashes to grow, it doesn’t help anything to grow. It is simply a good moisturizing ingredient, period. Lash growth (or any hair growth for that matter) has nothing to do with how moisturized the hair is. If anything, applying mineral oil to lashes will cause the mineral oil to get in the eye, creating a filmy, greasy mess. Not the best. Regrettably, there is nothing you can put on your lashes to help them grow.

Dear Paula: I enjoy reading your column. Your comments about the limitations and lack of scientific procedure for cosmetic company testing of their products always piques my interest. I have a personal story to share:

During the early 1990s, I was hired by a cosmetics company as a cosmetic tester. The company would give me samples of various new products to use and then I had to come in to be checked by a dermatologist for “results.” Of course, each time I went in I was also asked for a personal evaluation and filled out a form about how much I liked the product. I was paid a sum of about $25 or so per test, with the final compensation being tied to the number of times I had to come in during the testing period.

What I only understood later was that if I wanted to be called back to participate in other testing I was supposed to rave about the product. Silly me I thought they were looking for an honest evaluation in an effort to improve the product.

In fact, I sometimes found the products I tested too perfumed and some creams made my eyes sting. After honestly reporting my negative reaction a few times too many, I was simply not being called to do more tests.

That’s when I realized that one of the ways companies get to say how wonderful their products are is by dropping anyone from the testing panel who had a complaint. If you wanted to keep getting free cosmetics and being paid for using them, you’d better say you love it and leave it at that. So much for scientific studies! – Maxine, via e-mail

A: Your story is fascinating.

Paula Begoun is the author of “Don’t Go to the Cosmetics Counter Without Me (6th edition)” (Beginning Press, $27.95).