These are getting old and older and it’s getting harder and harder to find a good set. Most people are just looking for ones that aren’t broken and ones that aren’t yellowed, but I think that last part shouldn’t be as big of a priority as other parts. For me, the #1 priority would be to have them be free from cracks, stains, chips…etc on the exterior of the light. Yellowing, minor scuffs/scrapes to the lens isn’t a big deal as you can refinish them. Damage to the backside of the housing however isn’t something easily repairable so I’d look for a set that has a clean backside too.
One thing of high importance, which I don’t think I’ve heard anyone mention before is the inside of the lights. The inside of the lights have as much to do with how they look from the outside as the lenses do, in fact, maybe more. My last set was looking pretty sorry so I started to refinish them and upon doing so I realized it was the inside of the light that was making them look bad. The inside of the light should be free of corrosion, dirt, rust, and the reflective parts need to be in good condition. Anything inside that isn’t shiny and reflective is going to reduce light output and make the lights look dull. First of all some water had gotten into my lights and mixed with what looks to be rust or some other reddish material and was laying on top of the reflector inside of the light. This caused it to look dull, luckily this just wiped off. Second, the reflective material had actually started to deteriorate. Here’s an example of the deterioration:
Here’s an example of some of the reddish stuff that was inside
Same goes for other internal parts like these:
In this pic you can see that I covered the corroded metal with a reflective film. You can also see the gross and spotty reflection in the reflector which is caused from the corroded yellow fog capsule.
All of this seems sorta minor, but it really does add up. For mine I did a fairly extensive overhaul and they’re much much better now, but I also spent way too much time on them. Ideally I would have taken two sets and used the best parts off of them to make one really good set and one OK set and just sold off the other one. Refinishing the outside is easier than the inside, so personally if I was looking for another set I’d be more concerned with the rear plastic housing and the inside bits