there aren't very many crappy ones, but there are a few that won't be any better than a steel or aluminum fork in terms of ride quality.
one dead giveaway is uneven weave 'ripples' where it's obvious they just draped a weave over a mold and cut it where it needed a 'dart' like any other fabric. good carbon is weaved to fit not cut. also, good carbon doesn't ripple.
good carbon generally is carbon where it's carbon and not mostly aluminum wrapped in carbon for the crown and first third of the blades... but it's hard to tell that from looking. good carbon will be light and stiff fore and aft and beyond that i'd just look for name brands like reynolds and kinesis and alphaq.
speaking of "i think i made a mistake"
i just ordered an aluminum frame in black. then i was looking at builds online and i saw a beautiful one in white, then biking home from work today i stopped and saw basically that level built white one... it was really close to how i'd build mine, and i was thinking "gosh the white looks so good..."
but after thinking about it now i'm like, you know, i'm glad i won't have the same bike as someone else in town and i think the black will be nice looking but not as flashy, which is what i want from this bike.
no use in having or riding a bike that you're not happy with.