[quote=@Bishop]
If you notice, every spam post uses  ☆____☆ so just auto-delete every post who uses more than 2 of ☆ or who uses ☆____☆ 
In all my time here I haven't seen an RP use this image.
[/quote]

Some bots are designed to have a return ping (terminology?), meaning that if they get blocked on something, they'll switch up their posting structure. Same can be said about the user names. If they are making multiple post per account they can tell when they are actively logged in and when they are blocked they'll just create a new account.

One way is for the mods to look at the log-in emails, although its not the best way, it can help if the email provider is something obscure. There are many sites out there that offer temporary email services or non-public emails so a block could be placed on those providers.