Look for any obvious hack job repairs- especially stuff like butchered wiring or gobs of RTV all over. Those are my two biggest peeves, lol. If they have a toggle switch to run the fan, it's not a big deal. Not something I ever do, but I'm super picky about wiring.
Valve cover leaks are pretty common, but should never be excessive. The shifter will never be super firm, but it shouldn't be super sloppy either. Other than that, they're really no different from any other turbocharged engine. If you can, inspect the plugs, and maybe do a compression test. These engines rarely run really smooth (inherant to 8v 4 bangers), but listen for obvious misfires, knocks, or excessive rattling in the valve train.