The difference between hard work and abuse, to me, is a third person's judgment. Some guys get done shooting a tame pheasant on a pretty day and they immediately tear the gun apart and clean it before putting it in the case. Several of us who hunt hard all year were eating breakfast at a duck club when one of the "pretty" members pulled up and started cleaning his gun. A guy looked at the rest of us and asked if the season was over today!
Some guys change the oil on their truck every 3000 miles no matter what. Some every 4500, some only when the mood strikes them. Everyone has their own standard. Some would say that getting buried up to the axles in a flooded creek and nearly getting swept downstream was abuse. I'd say that was what turkey season. Some would say parking it all day in 2 feet of water was abuse, I'd say it was duck season.
The point is, some people love to baby their stuff, play with their stuff, talk about their stuff, and clean their stuff. Some people buy their stuff to use it, maybe abuse it, and worry about the consequences when they happen. Sure I want my stuff to last a long time, but I bought it to use, and my free time is worth a lot to me. If I can hunt an day or two rather than clean my equipment every time it's dirty I will. If that shorten's it's life, so be it. I doubt if I'll worry about the condition of my 4-wheeler when I'm 80. I suspect I will still look back on those hunts with fond memories.
To each their own. The judgmental tone of "gear guys" bugs me sometimes. I'll handle my gear, you handle yours. I may very well be the reason you should worry about buying a used quad. I'm ok with that.