Jason Aho rated Sting as 4 of 5 for in-person autograph signing
Sting was in Minneapolis in September, 2018 for a show with Shaggy. The two of them did a paid signing at a record store in town. They did a Q&A together before the signing and were very engaging and humorous. Attendees needed to buy a copy of their album "44/876," and that's all that they would sign. During the signing portion, there wasn't any time allowed for conversations or posed photos, but both Sting and Shaggy were friendly, smiling, and joking around with the attendees.
Jason Aho rated Roger Waters as 3 of 5 for in-person autograph signing
I got Roger Waters on three LPs in St. Paul, MN in July, 2017. I had two helpers, and he was good for one each. There's not really much to say. He seemed a bit annoyed, but signed. His handlers, though, aren't very pleasant people.