I've marked this "major" because I've had users try to remove what seem like duplicates from the search results. Unfortunately, they only look like duplicates.
The problem is joins with the tags table. Records with more than one tag appear more than once because joins returns n x m rows, where n is table one and m is matching rows in table two.
If MySQL's subquery performance weren't so poor, I would suggest using a subquery. A DISTINCT or DISTINCTROW in the SELECT would probably do the trick, though.