Not to derail onto an audio tangent, but people generally don't have THX sound at home. They have THX certified equipment. However, to have an actual THX sound system, it has to be configured along specific guidelines and tested for audio quality across the room being wired. Theatres do this to get THX certification on specific theatres for the marketing value (and maybe to entice audiophiles in some locations).
I doubt many home theatres have been configured properly or tested for certification.
THX is a certification for specific configurations of the environment and thresholds of performance of audio equipment. (sort of like the government security certifications for operating systems. They dont certify the os, they certify the os running on a specific configuration of hardware.)
All that being said, i've heard they are getting to the point where they'll slap the THX logo on just about anything for enough money, so even THX certified sound setups might not be configured properly anymore.
Having THX sound and having THX certified equipment means exactly the same thing, as THX is just a certification, like you said.
So yeah you're right, you just didn't abuse the language like I (and everyone else) did. Like I said, the certification at home and in theaters are not the same too. The certification for home doesn't take into account the speakers, the wires and the position of speakers.
So of course, if you're only used to the THX for theaters (the original one), you can only be disgusted by the THX (and its numerous light versions) for home. Just remember that it's not the same thing, even if the logo is the same, then it's fine.
Home and theaters have different requirements, and that applies in audio as well as in video.