Most TVs are set to terribly inaccurate and inappropriate levels of color temperature, brightness, contrast, gamma curve, etc. Incorrect brightness and contrast settings would easily overexpose the garbage mattes which would otherwise be relatively hidden.
When set more appropriately, using a setup disc, or even better, calibrated by a pro home theater calibrator, the garbage mattes will be much less obvious like it was in the movie theater.
Yeah, that really works with a movie that is properly transferred, like Se7en. But a lot of the time films don't look that great using a properly calibrated set. I mean, in order to watch the space scenes in INSURRECTION w/o flinching, I remember having to turn the contrast way way up and bring the brightness down, to get the ship windows to read like something other than fuzzy plain white mailing labels.
Pete Kuran is a vfx guy who goes all the way back to the original STAR WARS, and I remember in the 90s, after the first THX certified laserdisc of SW came out with all the garbage mattes, reading something from him where he actually had a good explanation for why the video transfers were hotter and thus exposing the garbage mattes. Can't figure out where it was he said it though, and am pretty sure it was a print source, not net. If I come across it, I'll chime back in.