Stay far away! There is a trend on trade servers for gamers to hold impromptu, unorganized raffles of random items. Often the raffle holder will have a small buy-in with the chance to win a valuable item. This item could be a hat or a bills. The chance of getting something valuable for a little risk encourages many to take the plunge and give away their metal or worse. Of course there is no guarantee that the raffle holder will pay out said item. If he or she does it may be to a friend to give the appearance of being legit. Then there is the buy-in, often described as "slots" remaining and so forth. Here also, there is no guarantee that once said slots are filled with buy-ins that the raffle holder stops taking more.
Stick to official raffles, held by reputable groups with real presences such as actual servers, sites and admins who are more public. Even here things can be sketchy. Spy-crabbing is also another game of chance, make sure to use a middleman for any spy-crab for anything substantial. The only true official raffle are crates of course. Any way you do it, use your noodle.
That is all. Be well. Have a good drop night.