Don't think there's much worse than having somebody ask for something reasonable in a bitchy way. If you say yes, you're a patsy and a pushover. If you say no, you're refusing to do something that's eminently reasonable -- even necessary.
If the request were made in a kind and appreciative way, it would be a pleasure to perform. If the request itself were unreasonable, it would be simple to say "No." But what do you do when it's neither?