If I test mine, it's just to see the reaction for myself, these days I always know what the reaction is going to be before I test it because quite a few people have already told me...
Add to that the fact that by the time a pill gets to me, I know at least a few people who've already had it...
However, if I ever happened to be in a situation where I knew no-one else who'd had a pill which I'd been offered, I wouldn't buy it... Past experience has made me too paranoid to be the guinea pig, not even with the testers to help...