Short answer: Yes, it bothers me a lot. Long answer: Being incompetent is not the issue as others already said. The issue is when people fail to realize their incompetency and even worse do not want to do anything about it. "They didn't even read my email" One of my biggest pet peeves at work. I am always amazed to see that people don't read important emails and will then call you asking for the same. Heck, they even…
I think this brings up a good point. I think most people just skim emails, they copy/paste stuff in, forward forwarded messages w/out any clarifications, etc and don't pay much attention at all to details. But I don't think the majority of these people are incompetent at all, they're just busy doing their jobs, and too many assume you as a programmer just know what's going on on both ends.
To help both sides, I've found that by expressing my desire to exactly meet what they want and asking that they always provide as much detail as possible things improve a lot. Also always providing good descriptive subjects and clearly formatted emails on my end, helps as well.