The enemies of VFDs from my experience over 30+ years (feel free to add to the list from your experience):
Voltage issues; surges, brownouts, spikes etc. As one old boss of mine said after getting orders for 200+ drives right after a large storm front swept through the South East one year," Lightning been berry berry good to me" (reference to Garret Morris on Saturday Night Live of old)
Heat issues; heat x time = failure. More heat, less time necessary to get to the end of its service life. Most people buy the VFD and scrimp on the packaging at the last minute. It's like buying a new Mercedes and then parking it on the street in downtown Oakland for a week. You might get lucky, but probably not.
Moisture issues; water from anything, i.e. not just leaky doors, vented boxes in hose-down areas or bad conduit penetrations, but consider condensation. A really common one is a VFD outside; VFD runs all day, turns off at night. Warm VFD, cool night air = instant condensation. If you use heaters, make sure some smart ass doesn't kill the power to save energy, heaters no worky without electricity; happens a lot.
Maintenance issues; "cleaning" is way too vague of a term to use on VFDs. I have seen more VFDs blown up because someone used compressed air to blow them off than I have ever seen from being too dirty. You should CAREFULLY read the cleaning instructions in the manual. If you want to use air, use EXTREMELY DRY air. The "canned air" for cleaning PCs and other electronics is OK as long as the propellant is not conductive (most are that way, just be absolutely sure).
Extreme cold; VFDs have big capacitors in them, larger ones are almost always electrolytic (cheaper) which means if the power is removed from the VFD the electolyte can freeze. If it does the caps blow the instant the power is re-applied. It's usually a big mess when that happens. To protect from that, you have to use a "freeze stat", like the thermostat in your freezer that is open at 40 deg. F and below, closes on temp rise above 40F, feeding a contactor that keeps line power off of the VFD line terminals.
Application issues; People often expect miracles and VFDs are good, but not "Messiah good". They cannot resurrect the dead or cure the diseased. Putting a VFD on a bad system rarely fixes anything, it just adds another device that can fail.