A high rate of failing caps (which can translate to power supply failures) are common to specific makes/models (e.g., AG-1980). As noted above, mechanical issues are more common as a whole. To add to latreche34's list some plastics (gears and couplings) and rubber (e.g., belts) are prone to go bad with age, glues may dry out as well, and physical alignment drift. Other threads here provide an indication as to the most common issues with favored makes/models. And previous owner misuse/abuse is also on the list (e.g., the classic PBJ stuffed in the cassette loading slot).
Note that being a recommended model does not assure any specific unit is good; rather it indicates its potential to be good.