I'm sure I used to have loads of stories, but it's been years since I worked on a service desk. Now most of the really fun calls are filtered out before they get to me...
I was once told by a guy in a finance team at our customers that I couldn't get access to a system to test connection speed issues on the Citrix system I'd just rolled out as it'd have to be approved and I'd need to sign various NDAs because of the confidential data.
I told him that's nice but if I wanted access I could just got direct to the database and look there, or make myself an account etc...
Same for emails etc. HR systems etc etc etc, the message is, if the admin wants to read your emails, they can... but you know what, the internet is a far more interesting place than someone else's inbox. (and even looking at porn on company time is less likely to get you sacked than reading someone else's emails.)
The calls that I get that are idiocy now are generally not end users being idiots, but either co-workers being idiots, or lazy... Occasionally we get the odd throwback from a really poorly implemented product... -usually when a customer starts asking for things to be removed from a design to make it cheaper. (basically, stuff that's annoying because it could have/should have been avoided)
An example of which is a few months ago I received a call that the SMTP server at a particular installation was not working. the guy was sending test emails but they were failing.
In the space of a few hours, someone had found an exploitable script on a web page and used it to send spam, effectively making one of our clients websites like some kind of open relay for mail. and they'd filled the bad mail queue and used all the disk space sending to bad addresses, (and sent who knows how many millions of messages to addresses that actually existed)
The developer in question suggested that fixing his code would be too much work, and we should just keep clearing mail queues, (nuts to our company getting black listed, and who cares that mail is going out advertising male enhancement or porn with our customers names on it?!).
funnily enough after a quick chat with a manager pointing out exactly what was going on, weirdly it wasn't such a big task after all and the guy could find some time to do it.
as for sales guys...
Sadly whilst we live in a commission based world for sales there will always be:
People who tell old ladies that they desperately need a mac book air packages with photo-shop etc if they want to email their kids and get pictures of their grandchildren.
There will always be salesmen who sell impossible solutions. because they don't need to implement the final product. they are long gone by the time that particular turd hits the fan.
Basically, what I'm saying is if you work in sales I probably think that you're a greasy weasel that deserves to bit hit with a spade.