sometimes a card doesn't fit into any part of your collection, but you buy it anyway and keep it, never questioning its existence among the rest of your cards. it's just...cool.
one such card in my collection is this 2001 upper deck gold glove jersey relic card featuring former astro (and dodger) cesar cedeno.
i stumbled across this card that i picked up from a bargain bin at a local card shop about 14 years ago while i was going through one of my monster boxes recently. i hadn't forgotten about it, but wasn't completely sure where it was at the moment. now, it is officially the first card in my 'cards that i like but don't fit into any of my mini-collections' collection, and is housed more fittingly in a binder page.
if you don't have some cards in your collection that are there just because you like them, i think you might be missing the point.