Well, trolling is I think largely based on intent. If one does not believe that they were trolling (i.e. they do not believe that they were doing what trolling

Well, trolling is I think largely based on intent. If one does not believe that they were trolling (i.e. they do not believe that they were doing what trolling is. This is a belief about what they were doing, not a belief about what the word "trolling" means), then that seems like fairly good evidence that they were not trolling. I don't know what would be a better (and available) measure of one's intent than one's own perception of one's own intent. (Of course, one could imagine that there might be a better source, but in practice I think it is the best evidence we have). This would only be as convincing to oneself I suppose, but I think that one's memory of one's intent is generally fairly good evidence to present to oneself to show that one was not trolling.