Every time I try to reply to this, it turns into something massive. In a nutshell, I reckon it's probably safe to apply a roughly symmetrist policy to making requests, provided the requests are in an area you're familiar with, and you understand exactly what it is you're asking the requestee to do.

I draw this conclusion from an area I'm sure a lot of LWers can empathise with: being asked for advice about computer-related problems from technically illiterate friends and family. I've come up with about half a dozen 'failure modes' for these requests, and they all seem to boil down to the person making the request not knowing the enormity of what they're asking for.

I'm reminded of the Dunning-Kruger Effect, specifically how the skills required to know how difficult a task is are the same skills required to actually do it. In the absence of the skill in question, (provided you recognise you don't have it), it's probably a good policy to simply ask someone how much of a pain the request would be before asking them if they'll do it.