I like to read comments and was wondering if there was a way to look for comments by certain tags. I know you can look up words but that's not what I'm trying to do.

Nope!

Ko-san said:
[...]you can look up words[...]

this is the only way...

If you want to search for a specific user, type "user:Name" in the search box or look at that user's profile (click the username) and click on the number right next to "Comments"