There are good bug reports, and there are bad bug reports. The good ones often come from people who have a lot of practice writing them. It's not obvious at first that you'll have to include information on how to reproduce a bug and what the expected behavior is. "X doesn't work" is a surprisingly common way to report a bug.
Ideally, as a software developer, you'd like no bug reports, because your application has no bugs. Since that's not the case, though, you'd probably prefer good bug reports to bad ones. Here's a trick that I bet will give you a larger share of good ones:
If you get a useful bug report, say thank you.
I used to work for a company that got tons of external bug reports. They all got into our system, but for the bug author, it was a black hole. No reply of any sort. I talked to several people who assured me they wouldn't bother writing in again. To them, it looked like we just threw it away. If it happened to get fixed later, who knows if they played a part in it? Unfortunately, I couldn't get it fixed at that company.
On the other hand, I recently wrote a bug report to Dropbox, and got the following email back:
Thanks for writing in, and I appreciate the feedback!
I'll relay this information to your development team, so that they can take a look.
Thank you, and have a great day!
(Thanks Matthew!) Such a simple note to write, and it doesn't commit to fixing anything, but it means I will write them back if I ever discover a bug again. If I hadn't heard back, I would probably not write back either.
The best feedback I've got is from sqwiggle, who not only give replies personally from the developers, but also turn around and fix it within days. I know that it's worthwhile spending time on a good bug report to them.
Bonus: I haven't seen this yet, but it would be great if bug reporters would get an email when their bug was fixed. A little reminder to them that you care and that the bug report was useful. But at the very least, show some love when you get a good bug report.