Would this frame make a good one for a fixed gear? Do those qualify as horizontal dropouts - I can tell they're not vertical, but are they "horizontal enough?"

https://columbus.craigslist.org/bik/98733367.html

it looks like a gaspipe frame (heavy and dead feeling) with stamped dropouts.
you might be better off spending a bit more for a nicer frame, but yeah, those dropouts will work.

thanks for the response. I'm not in love with the frame and would be inclined to agree with you, but now I know that the dropouts don't have to be completely horizontal in order to qualify. Thanks.

I'm with dolface. Keep looking, that is not a good frame. I had one similar to it, and it was really chintsy

Scroll down to "Vertical Dropouts" > https://www.sheldonbrown.com/singlespeed.html

I bet you could talk them down to $50 which wouldn't be bad for a beater in my opinion; but another issue is the wheels, which are likely to be 27" - which makes brakes and new tires messy and a more pricey ordeal than this frame might warrant.

Those are semi-horizontal dropouts.

in other words, diagnol?

I think those look exactly like horizontal drops to me (at least going by experience and Sheldon's site). But whatever you call it, as long as the dropout allows at least 1/2" of play, you can fix it. No matter what you call it.