I don't see why Adult##.com where ## is a random couple of characters is worth low 5 figures. Granted, HQ might mean headquarters or high quality, but I can find and hand-reg dozens of unregistered adult##.com names where ## means something for an internet biz.
In this strange case, IMO valuation can be one of these:
1) 48 mo revenue if traffic is good and solid.
2) 12 mo revenue if traffic is scarce and/or volatile.
3) Max offer received during 3 years parked.
4) Zero, if it makes no money when parked.