I'm a bit mistrustful of people I don't know personally, so I've -always- checked feedback and ratings, even on tiny things. Even then I'm quietly up in arms (I don't harrass until it's become obvious something is amiss) until I get used to them like I did Emory or I get the item. At this point with Emory/JS I just pay and (try to, ala anticipation) forget.
I don't take money very lightly - I grew up that way (I guess I can thank mom having once worked for the IRS o_O roflmao) so I guess it's ingrained.
Some people you talk to long enough or just see (...read?) long enough and get a sense of what they're like. I'd trust Kiki, Zircon, Mommieh, Grey, VV, etc, etc, etc (those just came off the top of my head), and so on just based on how they carry themselves - as well as the visual proof (such as seeing all of Kiki's faceups and her happy customers receiving them ala threads... I haven't even read her feedback page

)
I think the only time I blind-bought was from Migidoll, but considering how many people were ordering, in their forum layout of an ordering process, that lots and lots of people were ordering every time they opened for sales prior to the time I went for it..... so it kinda made it's own feedback.
That and DDE for my B&G Sharon, Reli. >_> That was a really nervewracking 2-3 months
Akihito [DZ Yuu], Red [ED Red], Sweetpea [DF Popo], Apollo [BBB Apollo], Reli [B&G Sharon], (phoenix) Efriete [B&G Afra], (human) Efriete [Migidoll Miho], Seth [Migidoll Ryu], Horus [Obitsu 50cm].
Do want: DR Xiao chi [as Xieu]; DOD Luke v2 [as Daven]; DIM Rain [as Rain]