The first time I heard of him was when people started complaining about his IMDb "reviews" of movies nobody else had seen, some of which were regarded as lost.  I do not ever recall encountering him at any SF conventions, but I usually stick to those west of the Mississippi.  I assume I would have rembered a 6'3", heavy-set guy in plaid pants and a sporran, and with bushy red hair and muttonchop whiskers...