FTJ is right - mold can be a huge deal, and not just in the brain-melting way. If you buy a house knowing it has or had mold, you'll have to disclose that when you sell the house. Sure, you can just tear out drywall, but to really get rid of the mold, you'll need to find a mold remediation contractor, and they're not cheap. When you get an inspection (which is a MUST, mold or no mold), find someone who does mold testing. They'll be able to identify the mold, find the source and maybe even help estimate the cost to cure. In this market, where buyers have all the power, I'd stay away from anything with mold. There are tons of houses for sale right now.