Ignoring things that are going to kill you / your partner here's my top 10 of rubbish diseases to have if you're trying to get laid:-

1) Shingles
2) Irritable Bowel Syndrome
3) Psoriasis
4) Acne
5) Tourette’s Syndrome
6) Dysentery
7) Seasonal Affective Disorder
8) Tapeworm
9) Attention Deficit Disorder
10) Head Lice

And 5 conditions that seem to be no bar whatsoever :-

1) Blind
2) Deaf
3) Obsessive Compulsive Behaviour
4) Consumption
5) Missing Limb