Most "avatarfags" belong to an interlocked network of "shitposters".
These "shitposters" are able to circumvent forced anonymity of boards such as /b/ through a Chrome/Firefox extension, "4chan X". 4chan X users can access a network, "Namesync", to monitor ID's of the user's extensions and allow ID ascription.
The equivalent of being a "Tripfag", but only to people using 4chan X and connected to Namesync.
Groups of related "avatarfags" usually participate in "circlejerk" threads, threads where they are the major posters, and post pictures related to the overall theme of their avatars, e.g., furry circlejerks include furry porn and comics; MLP circlejerks include screenshots of the show, "My Little Pony: Friendship is Magic