The way the bot is currently set up:
Anything with a cig gets marked
Anything with a gun (presumably) gets marked
Anything with curse words like “damn” or worse (even if only once) gets marked
Obviously porn gets marked (hopefully, not willing to test this out but I think it will given what was just submitted to msmg)
Anything that contains violent words (“suicide” and “kill””) gets marked.
Anything mildly disrespectful gets marked if the bot considers it so.
However:
Spam does not and shouldn’t get marked.
Wrong stream (as far as I know) doesn’t and shouldn’t get marked.
Political memes: depends on the topic. Sometimes just mentioning the word is enough to get marked, other times you can skirt around it.