I don't see any problem with offer something through PM! Important think is that check out its portfolio and get all info about that guy! Steve
it is better not to take offers in pms as you can't leave itraders on those! but then the new ones usually try to deal in pms because they can't start a new thread! may be scamming is not always there main intentions
Best thing to do is just report it as PM spam straightaway - forward to a mod who will quick dispatch the culprit.