For me, it depends on the race.
I train pretty intensely - to the point that I'll even get on the trainer in the middle of the summer if that will provide me the best opportunity to get my workout in. But sometimes, I am not racing that hard. I've even been accused of being chatty in races because I'm just talking to whomever is next to me. Often times, I don't get a response as they're working hard and not really able to respond or just put off by the idea of chatting during a race. Sure, maybe I could be going harder or attacking at that point, but I enjoy chatting too.
Other times, I'm the guy going so hard I can hardly see straight let alone talk.
And if I'm lapping someone, I'll usually give them some encouraging comment or tell them to hop on.