Anytime someone 'touches' your bags, they are going to feel entitled to a tip. I remember when we checked into the Polynesian. We had taken a towncar service there. When we pulled up, out raced a Bell Services CM. He took (grabbed really) our bags right out of the hands of our driver. He put them on the luggage truck thingie and then stood there...just waiting. My dh handed him $2...we had three bags. Then, yet another CM rolled the luggage into the lobby and waited while we checked in. He also stood there, waiting...and another $2 was handed over.
Then, once we were checked in, a third CM took the luggage from the lobby, over to our longhouse, where he also stood there, hand out so to speak, in our room. And another $2 was gone.
I know.....it's not about the money. It was only $6. And my dh usually tips much better than that, but he was really annoyed about the flagrant, in your face attitude of the Bell Services CMs. They were so obvious about wanting a tip and to have 3 different CMs move the luggage was incredible.
Now, we usually take our own luggage ourselves. I know that if I have a rental car, I unload it up at the entrance to the lobby at BW. And there is usually someone right there to help out. I tell them no, that we're all set. My dd stays with the luggage while I park the car. Then we bring it into the resort ourselves. If we have to leave it at Bell Services, then fine...we're prepared to give a tip. Otherwise, no.