1799 Silver Dollar

Absolutely. But how do you exercise that due diligence under these circumstances? I concur that the absence of a slab isn't proof that the coin is bad, but I'll go back to a comment I made earlier in this thread - why isn't it slabbed when that could easily double the selling price? So it's a red flag, and I think I'm doing exactly what's expected of a forum member to point that out. I also agree that the existence of fake and "basement" slabs complicate the whole evaluation process, but again, Stack's Bowers, Heritage, Goldberg, et al would absolutely no way ever publicly offer a coin like except in a reputable TPG's slab (even though even they can make mistakes).