i tend to think of the pwp spaces as more 'parents with babies'. i stopped using them when my son began walking and will do the same again with my baby girl.
most of the time i don't even bother and just park in a normal spot. i do hate it when i see normal, healthy young people park there but i don't see anything wrong with elderly people or people obviously sick etc. (eg. on crutches).
i DO wish that they would structure carparks with a small footpath up the centre where the two rows of cars meet so people don't have to walk behind cars in the driving lane. but then they wouldn't be able to fit as many spaces in
the only time i have ever said something to someone was when they parked in the disabled spot. i just think that is a really selfish, %$*# thing to do.