Basically Scott,
1) as mentioned, a household or even shop mirrors are only glass panels with a coating on the back, that would produce doubled reflections for astro, and why astro mirrors have coatings on the front !
2) again, household mirror surfaces & all mirror surfaces in general are very very uneven, both front & back surfaces, the front surface introduces bad reflections, & the rear surface which the coating is on, and not a great coating either, only surprisingly reflecting 50 - 75% of light - who'd of thunk
Anyway, but if thinking of them 'magnifying circular mirrors' for girls make-up etc, Lol , then they too are very very irregular on their surfaces compared to astro mirror surfaces, ( I know, I tried one when was young
- Imagine roller skating across a cow-grid, Lol . Honestly :-)
Astro mirrors are also polished smoothed to only a few millionths of an inch and we all know that they need to be 'shaped' accordingly, each with a certain central depth, ( Sagittal Depth) for the Focal Length to be reached & Parabolized to certain tolerances depending on size, and speed = F/Ratio
Hope this also helps,