If you go 3d models -> car -> filter to newest, you will see ( of course if you know what to look for) that 9 out of 10 models is stolen either from video games or from other designers. So it isn't hard to realize that if you post a project 9 out of 10 people will try to sell you stolen work. This is what most people who do business here realized long time ago, so one of the way to avoid thieves is by "using" trusted designers by asking on the forum, because community very well know who is thief and who isn't.