If you forgot to pull up your sweatpants and went walking around the store exposed and you were recorded on surveillance video, you may have a problem. You could be charged with indecent exposure or under the influence of whatever. But the store or law enforcement would have to be able to identify you. That is possible if you drove to the store and the outside surveillance cameras have an image of the license plate or you purchased something at a register using a credit card.
How does someone forget to pull up their pants?
It is not totally unheard of with elderly senile men to forget to put things away.
unless the op can prove they are mentally deficient and could have accidentally forgot to put things away I suspect op would be found guilty. The act without a valid defense likely establishes mens rea.
In one other thread, you reacting prompted the spammer to hit the thread again.
The more likely theory is it picked a random thread as it usually does and posted again. There have been plenty of threads that it has posted on that others posted after it and it didn't magically return.