There is no snipe dude. Ur just a troll victim.
The only ones I haven't seen online are this snipe people are talking about, and the hearse. In another post they say the hearse spawns online.
The tailgater and Schafter while uncommon are certainly not rare. My personal favorite "uncommon" car is the F620, it is an awesome car and I think one of the least common ones.
The snipe is real. You just need to truly believe in it for it to appear. The game knows if you don't have faith. It's kinda of like Santa clause, real if you believe but the second you start doubting it's existence all the majic goes away