Originally Posted by ralfp

Perhaps that's why they don't tell you about their use of drugs.

Unless you know very few people, I highly doubt that you don't associate with people who use drugs illegally. Many people who don't think they "do illegal drugs" probably, on occasion, do drugs illegally. For example, taking 1 more Percocet than the prescription dictates: that's illegal drug use. Getting one from a friend or spouse, that's illegal drug use.