The guns are used, sometimes abused. They are typically batch graded so the grade may only apply to in general to any gun you purchase. Here is a version of a grading system system:
VERY GOOD - Everything works, some wear on finish and working surfaces, minimal or no corrosion, but maybe some light freckling. Could have minor dents and scratches. Bore may not be shiny but should not be dark.
Modern guns = 70-85%, Old guns = 60-70%
GOOD - Working condition, but finish may be quite worn from sustained use or carry. Wear on working surfaces. Could have some pitting or light corrosion / freckling, and dings or scratches, but they should not interfere with function. May have dark, worn bore. This is the usual condition that surplus guns are graded.
Modern guns = 50-70%, Old guns = 30-60%

FAIR (or ABOUT GOOD) - Still considered working usually, though minor adjustment may be needed Well-worn finish, perhaps no finish left. May have corrosion or pitting that does not render gun unusable. Bore may be shot smooth and be dark. Wood may have cracks but is usually still usable.
Modern guns = 20-50%, Old guns = 1-30%
Previously I purchased a used Browning Hi-Power clone, sent the first one back due to inoperative safety. The second one had quite a bit of rust (former owner was a certain country's Navy). Cleaned it up, replaced the grips, still not beautiful but shoots quite well.

Decent project or beater guns. Just don't expect too much, and be ready to replace a small part or two.

The compact CZ75 is about $100.00 more than the fair used CZ 75 compact. The full size CZ75 (Omega trigger) is about $150.00 more. It will take more money than that to refinish either gun and put new grips on it. If you want a serviceable CZ75 to knock around and carry that you have little invested in I'd get the surplus gun but if you want a project it's not really worth it.

You may strike gold or you may break even. Minor holster wear or dogged out and dinged up. Its like buying a raffle ticket that promises you will at least break even. Some have said they did not get a magazine with theirs and others say they received two magazines. You will at least get your money back.

They are actually used, surplus pistols. A pretty sweet deal. Keep them as they are or have them refinished and you're in with a sweet pistol that's functional. Hope that helps!