My thanks to everyone who has weighed in. Yes, marijuana and alcohol are common on almost all college campuses. And, yes, guys on teams drink alcohol and some smoke marijuana. However, when my son visited other schools, no one offered him marijuana or alcohol His reaction to the guys who offered him marijuana was to call me during his visit and say he'd made up his mind that he was not going to go there, "I don't want to play with a bunch of smokers; I want to play with guys who are serious about the game." His only question is whether he should tell the coach what happened. He is going to tell his club and high school coaches.He will not sign with another school in the conference.
FWIW, and I know this happens, on visits, the recruit sometimes has to pass a "team" test. Every team does things differently, but IMO there is a difference in offering alcohol and offering a substance banned by the NCAA.
While its obvious that these things take place on campus and on teams, this definitely could be a reflection of the culture or an reflection that someone is trying to trip your son up. Just remember there is a difference between a recruiting visit for a young junior and a senior on an OV.
IMO, I would just move on because these experiences should be positive ones for him, not negative. Telling his current coaches what happened is the right thing to do, your son should not put himself in a position to rat on these players, remember its his word against theirs. It might be more trying to see not if he would say yes, but rather would he go back and tell on them. There are many things that happen, and the code of "I shall not rat on my teammates for any reason is perhaps #1". That's why on many teams, unless someone is in real danger, the team is left to police itself and take care of its own business.
If you are upset, I do not blame you, I would not expect my son to ever be put in this situation.
BTW, marijuana use is frowned upon in MLB, but players testing positive, unless a second offense, do not get suspended.