Allow Comments in For Sale Ads

lets say, just a hypothetical, that i know this truck (i dont) and its a POS (and it is NOT a engine swap assembly, not with that truck pan, it aint)

[FOR SALE] - 318 engine swap assembly. Edelbrock to oil pan, 727 trans located in San Jose, Ca. $500

could i start a thread in the mopars section, calling out the seller?
can i comment on it that way?

or are for sale adds completely off limits?

what if a someone with the screen name of "justin figgot" came online, and posted a for sale add, can i post an add in the main forum telling people this name sounds familiar and not to deal with him?