best way to spot a repaint?

[ThePhreaker]

for example black car repainted black..

I know to look for stickers, emblems, is there anything else?

 

[NJVetteGuy]

If it's a non-show quality repaint, you can usually find the paint lines around some of the moldings and rubber parts where they taped off those parts. Paint on rubber parts from a bad tape job is a dead giveaway

 

[Gary Wells]

FWIW & IMHO:
overspray
Paint too smooth in general: (no orange peel)
No errors in the paint job in general: (no pinholes, for example, in top coat),
Car surface too smooth & straight where it shouldn't be: the intersection right over where the side is almost to the top between the windows.
Door jamb area, paint looking a lot nicer & fresher on the exterior compared to the door jamb areas of the car.
Difference in hue & quality between the car exterior paint in general & the paint quality & texture & color under the trunk lid.
Difference in quality, color, &/or texture of the paint on the hood lip area on the "sides" of the hood as compared to the hood in general.
Factory hood, (does the car have a part # on the passenger side side of the hood towards the rear of the hood), no number there would indicate at least a non-factory hood, requiring a paint job on the hood as a minimum.
No holes in the paint, (sand-through) especially in the non-black cars in the area just over the headlight bezels before the hood.
(top of header panel area).
Any mudded in areas?
Shouldn't have any paint build up thickness issues in the area of directly around the rubber surrounding the quarter windows than directly underneath the rubber. (different paint height) oops.
HTH, & no flaming intended regarding anybody's paint job.