Do You Use The Handicapped Stall In A Public Restroom?

There was a post on Facebook about a woman using a scooter in a grocery store when she was merely "tired", and many people are commenting. One of the comments mentioned using the handicap-equipped stalls in public restrooms.

When you walk into a public restroom and all of the stalls are being used except for the handicapped stall, is it okay to use that stall if there are no wheelchair-bound individuals waiting to use it?

When you are approaching a business, is it okay to walk up the wheelchair ramp instead of taking the stairs?

When in an airport restroom, is it okay to use the handicapped-equipped sink when all of the others are occupied and there are no wheelchair-bound people waiting to use it?

I guess that what I am getting at is this: my parents taught me to be as accommodating as possible when I see someone who might need help, whether it be to outright offer assistance, give way when they are trying to get by, or alert others to take notice. If I see someone with a cane or wheelchair or crutches (or with obvious mobility issues) I always try to help with doors or chairs and whatnot. But what about a public restroom?

If I walk into a public restroom and all of the stalls are in use except for the handicapped stall, is it okay to use that stall? Or should it stay open, just in case a wheelchair-bound individual enters?

I'll admit that I HAVE used the handicapped stall when the others were occupied, but, believe me, it was only because of an urgent situation. In all other cases, I avoid occupying the handicapped stall.

What are your thoughts on this?