I've got one of those handicap placards for my mirror too. Sometimes I'm in my wheelchair and sometimes I'm using my quad cane, slowly with the help of my wife, walk when I can for short distances.
If there's a parking spot just as close I have my wife not take the handicap spot so someone who needs it more than I can have it.
It really aggravates me to see someone unthinkingly take that spot when they clearly don't need it.
But then again, it doesn't exclude integrity!