I used to stress over the bad comments and ratings. Now I have so many ratings on my apps, and so many comments, one guy doesn't have any impact. I've actually had my best sales day when a terrible comment was the first comment on the "lite" version of the app.

Also, the lite/free versions get really hateful and terrible comments often. The people who like the app seem to rate, but not comment much of the time.

Long story short, I just don't sweat it anymore. I don't even think people read (or at least believe) comments, especially the ones that are just mean.

I just try to build a great app, take the good with the bad, dwell on the positive comments, look for insights into problems in the bad comments, then ignore the rubbish.