Well my frunk hood was replaced last year and I found a guy on Rennlist who's in Spain and makes a very nice reproduction option sticker that I bought and installed.  On the 986 there are also 2 other dark background stickers under the frunk hood, one is a caution label and the other is A/C information.  If those are missing too then I'd say the hood was definitely replaced.  But I bought replacements for those two stickers from Porsche as well.  See this 
thread from when I replaced them. Having the stickers in place isn't a guarantee that the hood wasn't replaced!  And Carfax may not have accident repair information if the work wasn't paid for by insurance coverage.