As peeples stated; It really depends on the "disability". Your goal should not be to "shock" or make the person feel "guilty/shallow" or uncomfortable. If you are blind, have a hearing problem, missing limbs, missing front teeth, unable to articulate words, uncontrollably drool when you eat, impotent, have burns over 80% of your body....etc These are some things you may not want to list in your "profile" but it is wise to let the other person know (early on) in your "getting to know you" emails and chats waaaaaaaaaaay before you meet in person.
Lying by ommission is still lying. Trying to trick someone into building an "emotional connection" with you prior to dropping (the bomb) on them is an act of manipulation. Ideally you want someone that knows what they are getting into prior to opening up their heart.