Email filters and spam

Ok, I don't understand spammers. I really don't! If I go through the trouble of setting up an email filter which blocks the word mortgage or loan or viagra, etc. then I think it's obvious that I don't want to see the email. But spammers come up with m0rtgage and L0an and V1GRA, or m.or.tga.ge or other stupid stuff which convey's their message quite clearly. BUT I DON'T WANT IT! If I went though the trouble of setting up a filter, then I'm not going to buy the spam's products (or even read it) when it comes in the mailbox. I'm going to delete it immediately.

I understand that the spammers are trying to sell their products. I don't see why they don't get the clue that I shouldn't have to deal with their emails. Besides... Selling something like vîåg®ä just makes you look stupid to the point of me not possibly wanting to do business with you...