I had an interesting experience once at my job.
I am hearing and at the time I worked in the gift shop of the local zoo. We had a group of deaf adults come to the zoo. A lot of times groups plan ahead so we know what to expect but not always. This group did not plan ahead with us, which isn't a problem although I felt REALLY stupid when I kept trying to ask a gentleman over and over if he needed help when he wasn't looking at me (I did finally realize he was deaf).
I felt bad though because I could not talk with this group. Most of the group wouldn't even make eye contact with me and just waited until the price showed up on the screen and handed me money. The only thing I knew how to sign, since I hadn't had any ASL classes yet, was "thank you" so I could at least sign that to them. I really felt bad because it seemed like this group, because of their response of not looking at me, had been treated badly or just mostly ignored in other places.
Do most people, in a customer service environment, ignore deaf customers? I hope not! Even though I was very ignorant in the above situation I still wanted to make an attempt to be polite and friendly. ::shrugs:: I still feel bad about it!