So "liking" real ale and being a member of CAMRA makes you knowledgeable enough on the subject to appear on Mastermind? You crack me up!
You love cats? That makes you an expert on them, of course, silly me.

I own and run a
very rubbish dating website.
Your site sucks mate! How many page views a month? Come on, impress us all
If that is the case then I am an expert in:
Comics of the 20th Century (I used to get a Beano subscription and was a member of the fan club)
Entomology (I used to have a pet stick insect)
Expert Perl Hacker (I once installed a form to mail script on a mate's website)