Most spam looks like spam but is constantly mutating to get past the spam filters that look for specific words or hashes or text patters that don't usully occur in a legitimate email message.
There is another class of spam that is just a simple advertisement or newsletter which is really legitimate to some people but if you didn't ask for it, would be considered spam. This type of spam can't really be filtered for with a general fingerprinting or pattern matching filter.
Your best best is to try a white listing service that only allows email from a certain list of senders. Everyone else would have to send a confirmation email to get on the list. Do a websearch for "whitelist service".