Typical fanboys often have outdated or unreliable sources that they pick only because it flatters their "model", and will often bash down anyone who disagrees with them. Most users will attempt to prove the fanboys wrong in a scientific argument, and this sometimes works, turning them into contributors. However, in most cases, it does not. After that, most users just ignore them or attempt to chase them off.
Although Fanboys are technically trolls, they usually pose no threat to a forum's safety and are best ignored.