Is there anything special to look out for when inspecting a 1970 Dart Swinger?

It's a flipper. I bought one a bit better than that but very similar a couple years ago. While I am, overall, happy with my car still, I have learned a lot from the experience and would be more picky the next time around. I have fun in it and all but wiring hacks are a pain to fix, shortcuts flippers use to make it good for pictures are much harder to repair than the stuff they were originally trying to cover up for. I lucked out with a NV desert solid, rust free chassis and straight body with good floors,though the black paint they sprayed all over made me scrutinize it closely. Yhat eas important here in rust belt. Minimal bondo in the drivers rear quarter and no rust about the windows. The trim and weather seals all need replacing and it is not water proof. The stroker drivetrain and 727 trans were well sorted and manual disc setup on all four corners is sort of safe. I spent about what your ad is asking. The fact that he immediately dropped his price in conversation shows he thinks the market is weak for what he offers. If you still like it, offer him less than you will ultimately go and don't settle for 15. Just my 1.5 cents. Good luck.