It seems often times I can't retrieve the correct game from thegamesdb (for example if it retrieved the wrong platform) until I've renamed the current title to something else, saved it, then go back and try to retrieve again. As if it's already in the database as the correct name and doesn't want a duplicate and I have to clear out the old one first before it can show up in search results.
For example, NBA Live 97 for SNES. It retrieved Genesis boxart. I go to edit it and search the correct title, but only NBA Live 95,96,98 appear -- skipping 97. I rename it as 'NBA blah' and save. Go back and edit again, now NBA Live 95,96,97,98 appear and I can select the correct one.
Not a deal breaker just an extra step I'm having to do to fix for 100+ titles
Edit: Sometimes just reselecting the same game from LocalDB and downloading images again works too. Odd.