I'm not sure of any specific rules. I usually use the QUOTE function to show quoted text, or enter it like this.
"... quoted text here..."
I will quote the part that is relevant to my reply.
It could be considered a TOS violation to manipulate quotes to make it appear someone said something other than what they actually said.
"It is easier to fool someone, than to convince them they have been fooled."
For those that don't get it, it means that people need to be more careful, and do good due diligence.