A few people on here have said that they don't trust vendors who were on the compromised markets, as they could be be in LE control. As far as I can see it, if a vendor was on a market that was seized by LE and practiced at all decent opsec (i.e., not using the same login on multiple markets, mixing coins, etc.), there isn't any way to tie their account on the seized DNM back to them, and no way to take over their sister accounts on other sites.
Basically, are there any legitimate reasons not to trust reputable vendors who sold on markets that were seized?
there's no way to know the opsec of your anon friends.