In some forums some forms of trolling are accepted, but the typical troll is an attention seeking nuisance, whilst the worst cases are hooligans and vandals. Asks basic questions that have been asked a thousand times before. Can't tell sense from nonsense. Doesn't realise, or doesn't care, that his messages are cluttering up the mail boxes of thousands of participants. Spam is usually commercially motivated, but this is not part of the formal definition.
Virus hoaxes are also a problem.
This article is intended to be humorous. But it does have its serious side. The types described here are parodies of posters to investment bulletin boards. Anyway the author hopes that this article promotes a little healthy skepticism about material posted to investment bulletin boards. Acknowledgements Thanks to Michael Dutton for his suggestions.