That sums it up pretty well. It all depends on what you do with the games. I know that a lot of Neo Geo collectors only "collect" Neo Geo games, and that's why everybody that sells Neo Geo games is always using a rating scale. I, personnally, don't give a fuck about the condition of the cart, as long as it works, though I like to have the case with it.
Personnally, I almost only buy the good games because I got a Neo Geo to play, thus the reason why I don't care much about condition. My dream collection for Neo Geo would be :
All Metal Slugs
Garou : Mark Of the Wolves
All Sengokus
some Samurai Showdowns
Last Blade 1 or 2
Nam-1975
Miracle Adventure
maybe Top Hunter (never played)
Of that list, I presently have only Metal Slug 3 and 4, Garou, Miracle Adventure, Nam and Sengoku 3. I do, however, have a couple of shitty games (like 3 Count Bout) that I will probably get rid of in the future.