Lots of levels to this question
(1) The overtly sexual/mature pose in stages of undress is quite uncomfortable, you are half tempted to give a gentle reminder that it is a probably not a good thing.
(2) The ego boost/attention seeking ones - I don't mind them so much par for the course with a lot of teenage girls.
(3) The need for an ego boost / will a guy ever date me - Sometimes people need affirmation and it is a bit cold to deny them that
I understand your concerns probably even agree with 99% but how do you control ban all under 18s from HDIL then group 3 suffer as collateral damage and I believe any boost they get from their question is very worthwhile. Again it is a numbers issue but I would have admin vet every question in HDIL question and remove any posts by anyone age, any gender
(1) In clothes you would not wear outside in company
(2) Comparison pics
(3) Third party pics
(4) Lastly only allow headshots or full body photos