Take another look at it. Used is probally the best way to get a Colt 1911. That price is reasonable.
Close your eyes and drag your finger nail across the scratches. If you can feel them, pass, can't feel them...buy it. 1911 finishes scratch. That's just the way it is. Hard, strong 1911 finishes are quite expensive and not usually found on 1911's under $1500. But I avoid deep gouges as they'll be harder to bead blast out when the 1911 is eventually due for a refinish.
Keep in mind you can cut down and re-shape the thumb safety. One of the reason why the Huge Ed Brown big paddle safety is popular. It's too big for most everyone, but you have plenty of material to work with and shape.
When I buy a used gun that I can't shoot. I let them know that I'm a serious buyer. "Can I by this gun used, and if It runs like poo, can I trade it back in, as long as a order a new 1911 from you?" My local shop will let me return a 1911, it's allready used anyways, as long as I'm buying something, and they know I'm not going to put any further abuse on it . Since I'm a regular customer...... But they aren't so nice to lesser customers.
The loose slide fit is normal for Colts. The under $1000 1911's are pretty much better off that way. Save the tight fit guns for the Semi-custom market where they builder can spend more time getting it right. Just make sure the barrel hood can't be moved easy when the guns in battery.
This advice assumes you allready have a Glock, M&P, etc. If a defensive gun is needed on a budget of $600, those are safer bets.
I prefere the series 70 without the silly FP safety. Something to look for. The 100 year special model GI reproduction is tough looking and a Series 70.