Newbies need to understand a very simple truth: there is no such thing as free and fast, i.e., easy money. OP is talking about a newbie sending PMs to newbies, but I would say that anyone who offers a rather strange idea for earning money that seems very tempting should always be suspicious.
Newbies receiving such PMs, of course, should not trust strangers. In addition to the fact that you can look at the posting history of the person who sent you the PM, check his trust, and boldly report it to the moderator as "unsolicited PM."