this is the one anon. Easily the best option. Might need a bit of work/ tweaking but well worth it. Very nice bike. https://sandiego.craigslist.org/nsd/bik/d/carlsbad-lemond-zurich-carbon-fork/6933569172.html
also a very nice bike. maybe too small. https://sandiego.craigslist.org/csd/bik/d/imperial-beach-nishiki-modulus/6933036343.htmlhttps://sandiego.craigslist.org/esd/bik/d/el-cajon-1983-trek-630/6922423366.html
these two look better condition, but less modern, and lower tier, and more money.
main thing to look for, is the teeth profile on the chainrings. Compare them to each other to spot wear. Blatant sharktoothing, so sharp points is terrible, and ones that look new are great. If they're fucked, as they often are on road bikes (more likely even with more modern higher tier bikes as they get ridden into the ground by roadies), it means you need to replace the whole drivetrain basically and it's expensive.
other than that, check the bearings are all smooth with no play, and that the wheels spin straight, with evenly tensioned spokes and not badly worn brake tracks. Check the legs down bend back from the line of the frame's head tube (front end collision). If you can ride no hands, try ride it no hands. That means a frame is straight. If you can't it's not necessarily bent though. Check all around for hairline cracks in the frame. Cracked cables.
Obviously how it rides. Most things are haggling points rather than passes though, except frame damage, and maybe bad wheels and badly worn drivetrain on a cheaper bike too.