In my case I'd say yes, they prematurely affect the life of the UPS but in my situation, all the electricity is supplied 365 days a year by generators. Some of my sites have no local electricity so we use ENORMOUS generators to supply the whole factory. We noticed our UPSes fail quite often because the power is not always "clean" making the UPS work much harder (going on battery more often). We also put a regulator in front of the UPS. The high temperatures and sandy environment doesn't help either. We've had numerous exploded power supplies to the unstable power source.