all my neighbors have ice dam problems they appear to be ignoring but that doesn't mean I should follow suit. maybe my neighbors are just particularly stupid. doubt it.
sure, IF a basement does not have a moisture problem, a carpet could be fine. often, a basement will have excessive moisture and this isn't even noticed until it becomes a big problem. you should at least advise dave to test the concrete first by cutting out a piece of poly sheeting, taping it to the concrete, and checking after 24-48 hours for moisture. dave should also know that lots of people have had to rip out carpeting because of flooding from broke pipes or wash machines, and this is something he should consider.
basement or not, carpet harbors more mold, bacteria, etc. than any other flooring. i just wouldn't use it.
the following exchange is at www.allernet.com (http://www.allernet.com/questions/q69.asp):
I have a question about the carpet in our basement bathroom, which smells pretty strongly of mildew. We have tried spraying it with a bleach solution, but it didn't help. Is it necessary to remove the carpet, or are there other alternatives to remove the mildew?
My 2 year old is very allergic to mold, so it is important that we address this soon.
Thanks for asking about your moldy basement carpeting.
Most likely your basement carpet is sitting upon a concrete slab. This situation allows for condensation to occur, which promotes growth of molds. It is common knowledge that moisture accelerates mold growth.
There is a good way to prevent molds from living in your basement. First, take out all the carpets which are placed upon cement. Secondly, do your best to reduce the humidity in the basement by using a dehumidifier in the area and keep it running for as long as you need it.
All you can do is your best. If these measures fail, then you may have a greater water problem than you first thought.