As I have said before, and this is by no means factual or scientific, but I would venture to say, "most" of the stated dates are probably accurate.
I have seen DOB's from one day old to over 100+ yrs. Obviously the extreme dates seen, those applications are deleted.
With the Privacy Issues out there, it will be very difficult to impossible to find and verify a DOB given.
If you suspect an applicant is a minor, you have two choices. Engage the posting or ignore it.