Over 100 mobile devices at our company and I'm the primary person taking them into the stores. I've been to 38 different Apple Stores in four countries and blah, blah, blah.
Wow, I'm actually surprised you haven't had devices replaced without a Genius replicating the issue(s). I see it happen all the time and I've had a few myself. On that note, I've also had an iPhone replaced just because the Genius said I was having app crashes and he'd rather swap it out than try to restore the software. I've also had an iPad replaced for Wi-Fi issues they couldn't replicate in the store.
If someone can't handle doing what I suggested (which I do to those 100 devices daily) then perhaps they shouldn't have their device.
Suggesting that someone shouldn't have their device if they can't do "X" is straight up wrong. Just because someone doesn't know how to clean, backup, or even use it, doesn't justify them not having it. If someone doesn't know any of those things, why not teach them instead of saying they shouldn't have it?
Do you tell them to drive an hour (when clearly they are trying to avoid that if they can) to have an expert clean the greasy fingerprints off their iPad because noob owners shouldn't be touching their iPads with a damp cloth to clean that either. Actually you probably do.
Yeah, I tell someone to drive an hour to remove fingerprints.
Seriously man, get real and lose that crappy attitude. You suggested using liquid on an area than really shouldn't have any liquid near it. If someone is suggesting using liquid on the front of the device around an area that shouldn't be wet, yes, I'll tell them to go have a Genius look at it. Especially if they are still under warranty. Why risk voiding your warranty for an hour's drive?