Certo6, a reputable camera repair and online seller can be trusted for folding cameras. I bought a cla'd folder from him. It is great.
I just purchased a TLR camera that was recently CLA'd (within the last few months) by Mark Hama. This camera is being sold by an individual. My anticipation is that it will be great.
In the past, I bought a Voightlander Bessa II from a camera seller in the Netherlands (the name of the camera shop escapes me right now), but they performed a CLA on it before posting it on eBay. It has performed great.
Every purchase on eBay requires some scrutiny, but so far my experience has been good buying cameras serviced by the seller. In the first case, the reputation of the name is well known. In the second case it was an established camera shop with a strong rating. I'll let the forum know in a couple days how the Yashica 12 tlr purchase works out.