that's not necessarily true. studies have shown that since the locals to these reefs have realized the monetary value of them, they have been taking better care of them. in some cases, the use of wild colonies has triggered much needed maintenance.
i really don't understand how a person can say a piece of coral is "self sustaining". i don't care where it's grown.
ultimately, if you make this hobby attractive in the least, you are hurting the reefs. no matter what corals you buy.
that said, the only way you can be sure you are getting aquacultured corals is by buying them from a local reefer that has grown them in his own tank.
many vendors are simply purchasing wild colonies, fragging them up and gluing them to plugs, and as soon as they encrust on the plug, offering them as "aquacultured".
and let me change the above statement to "most" vendors. i only know of 1 supplier that actually grows their corals prior to selling them.
as far as hitch hikers, these can be picked up from wild or aquacultured colonies. if you are quarantining your corals, you don't have to worry about this at all.