The response I received from famousforwrongreason undelines the very reason why I am sometimes reticent about revealing my sex when I post on a thread! There are certain subjects which interest me and it is interesting to see and receive differing views, opinions and thoughts from others on the same topic. Good enough reason to use Mumsnet, I would have thought!
In response to the OP's original question, the following are what would be offputting for me. I no longer use dating websites, since I am now in a happy, settled relationship with my lovely partner and wonderful stepdaughter, and my dislikes are, of course, purely subjective, personal preference and not set in stone. But:
Tattoos - dislike them intensely on both men and women.
Profile pictures adorned with bunny noses, whiskers, halos of stars, flowers etc - too 'cutesy'.
Those who describe themselves as wanting to be treated like a 'princess' or 'queen'.
Those who like an urbancentric lifestyle - I am very rural and countryside focussed, therefore we would not be compatible.
Those who are in search of a 'knight on a white charger' - such things do not exist!
Those who list hobbies as shopping, eating out or are clearly very sporty - again, lack of compatibility.
That is it really, good job we are all different!