Just for fun:
The first post is usually long, designed to either sell something or upset the majority of the board.
There will be excessive use of formatting (the post is usually prepared well in advance). Lots of bold, font size changes, color, underlining etc.
The content will be suggesting things that are usually diametrically opposed to the content/purpose of the board.
If ignored, they usually go away.

If they persist, they are usually banned

The slide from grace is really more like gliding
And I've found the trick is not to stop the sliding
But to find a graceful way of staying slid