[Wylie's Mom]

Originally Posted by Little Bit

When questioned she just has to tell them she is a service dog and show the letter if necessary, but legally they can't even ask what the problem is that the dog is for.

This is EXACTLY right. KNOW your rights. Here is a link to a one-pager that contains all the info for bringing service animals into businesses: http://www.usdoj.gov/crt/ada/svcabrs3.pdf

And here is an important piece of it:

"Businesses may ask if an animal is a service animal or ask what tasks the animal has been trained to perform, but cannot require special ID cards for the animal or ask about the person’s disability"