Since I'm the first guy to use the word I'll provide my definition of 'junk' as it applies to Palmetto. Keep in mind this is my experience plus impressions from postings in various forums.
Finish is average to poor. Burrs, machine marks, uneven bluing, nicks, gouges, etc. Grips looked varnished.
Fit, especially grips to frame, poor. Cylinder lockup ok but significant end play that could not be solved by seating the wedge, suggesting arbor either too long or not seated in frame. Hammer was not centered in frame. Timing poor, in that chamber alignment with bore was poor. Also, full cock was premature. I did not disassemble either gun I examined.
Function: did not shoot either example I examined, nor have I ever seen a range report on one.
I believe the fit and timing problems could have been corrected but the finish would have needed complete disassembly, stripping, polishing and rebluing. The grips were not salvageable, but they're not expensive.
I have no information about reliability over time.
I should say that you can get a lemon from anyone. Lemons from Colt are extremely rare; if there are any left out there that have not been repaired by some aficianado I'd be shocked. Lemons from Uberti show up from time to time; I'd say they are quite unusual but not rare. Palmettos seemed to be the norm rather than the exception, with 'nice' Palmettos being the rare case.
Of course, the above does not apply to used guns; any gun can be abused into poor condition.