Most of my characters are kind by default and I've never really felt like the responses completely shut down the ability to be kind. It might be how you interpret different lines though.
For Volo, you can answer his questions. I usually do. Either giving him correct answers or giving him blatantly outlandish ones that he's clearly after. I always interpreted that as the player character is in on the "joke" as it were. We're humoring him either to be nice or because we also like to embellish our stories with outrageous flaws. I've never felt like I was outright rude or dismissive of him unless that was my goal.
For Wyll with the goblins... Admittedly I don't travel with Wyll much. I don't remember this convo very well.
Wyll at the camp though? He's kind of telling you something obvious. It's common knowledge not to make deals with literal devils. I've always taken that as him being a bit condescending to me, personally. He thinks I need a long story with a morality lesson at the end to know that beings of pure evil are not to be trusted just because he was dumb enough to do it himself. Even then, I didn't feel like the choices I made at the time were especially rude. I more or less agreed with him and moved on.
I do recall stopping to save Shadowheart on the ship, though. And talking down a snake to spare a child's life before saving another child from harpies. I stopped to tell the Tiefling kids an inspiring story and took time out of my busy day to instruct another Tiefling in how to do a thrust. Each time I was polite and chose not to ridicule anyone. Just a gentle barb or two for the sake of good humor.
I did make that kid flip the coin a dozen times, though personally, I felt like that was a sort of Dad Humor moment. Afterward, I made a point to purchase from his shop and didn't get mad when they eventually stole from me. I even stepped in the path of a crossbow to save the life of a goblin prisoner purely because I felt it was the right thing to do.
There might be a few dialogue options without a super nice option, but at least for my experience I've never found it hard to feel like a genuinely good dude playing this game.
