PN, Skeleton and in particular TrimStab,
Sometimes the disablement is not always obvious. I have a friend, also an ex serviceman, who has terminal cancer. Sept 2012 he was given from 3 months to 5 years to live. He is 41 and from looks alone you would not guess he is terminally ill (though you would think he is a lot older than he actually is).
He is quite often in severe pain but he does have good days.
He is a fighter though (as one would expect from an ex serviceman) and refuses to give up, refuses to allow his illness to stop him (when he can). He doesn't play golf (trim stab) but he does try to help round his fathers farm when he can; last month he even went sea Kayaking when visiting friends in Plymouth.
He insists on living life as much to the full as he can while he is still around (he has 3 children and wants to make as many happy memories for them as he can).
He has a Blue Badge because of his Cancer and also because of the sometimes terrible side effects the Chemo has on him (he is on chemo not to cure the cancer - it has been acknowledged that they cannot cure it, but to prolong his life for a few extra months and also to get some research put of him as he has a rare form of cancer). He has been taken to task a few times by people like yourself who question his eligibility.
Only once has he snapped, when some 'do gooder' would not let it rest (he was with his children at the time) and he was feeling particularly low as his chemo had been stopped because of the side effects. He turned round to the buffoon and told him where to go in no uncertain terms but didn't feel proud of himself afterwards because he acknowledges that some people are just idiots...
I'm sure there are plenty who abuse the Blue Badge, but please think twice before taking in upon yourself to police it.