I have been a member of OKCupid for 4 years and only really became active earlier this year. I have met several genuine women there. I have been approached by African scammers there and others have reported it as well.
A free site that allows you to contact other members is going to attract scammers; you just need to be careful and use common sense.
One thing that is good about OK Cupid with respect to scammers is that experienced members are granted moderating privileges and can 'vote' to have suspicious profiles/pictures deleted. The people there are very savvy. It is there that I learned about Tineye
, which lets you check to see where pictures you find may be posted elsewhere.
There are also discussion forums where members can exchange information.
I look at OK Cupid as any other public place; there are good, bad and indifferent people there, so you conduct yourself accordingly.