I have owned a couple 1911 models and I love them. There are a few "tests" that can be performed to see if the gun is tight. Now whether or not these are tests that truly determine if a gun is wore out or not I can not tell you this but I feel they make sense. Not in this particular order but here are the ones I can recall off the top of my head,
1. lock the slide back and shake the gun, this gives you an idea of how tight the fit is between the slide & frame as well as any other matting surface.
I believe in this test because I had a kimber that made hardly any noise at all and I now have a cheaper 1911 and in this position it rattles a bit.
2. with the slide forward in battery put your finger on the barrel and see if it moves. basically you are checking the play between the barrel bushing and the barrel.
I know if you go to youtube there are a couple videos on what to look for I can not recall any of the others right now, I believe the video I watched showed about 5 things to look for in 1911 model guns. I hope this helps a bit and good luck finding what you are looking for. Love gun shopping!