Here's how you can hide comments on web sites in Firefox with the free addon CommentBlocker. This can make browsing the web more pleasurable as some comments on sites can be nasty, abusive or just a plain waste of your time.
1. Go to the CommentBlocker add-on page.
2. Click the Add to Firefox button.
3. No restart should be required after you install the add-on.
Here's part of the official description of CommentBlocker:
"Have you ever found yourself frustrated while reading some stupid comments written on a website? We've all been there. This addon, CommentBlocker, is the perfect solution for us who get annoyed daily on comment posts.
The addon is customizable and lets you choose wether or not to blacklist or whitelist specific websites. This means that when used with its default settings, CommentBlocker will filter out and block all comments on websites that you visit. It then lets you choose to view the comments live on the page with one mouse click, or to save the website in the whitelist, making it always show comments on this website."
Read more: Ghacks