I'd say yes, if we are talking about these boots worn anywhere other than as gear or around the house when it is freezing outside. I hope that's not taken as a slight to your mom - I've just really disliked the look ever since the boots first made an appearance (worn with super short skirts or shorts) while I was in college. I don't think that they are flattering to the leg or the foot.
However, Ugg also makes some legitimately cute boots that don't look like sleepwear. I could totally see these working well, for example:
http://www.uggaustralia.com/Pr.....l=Amberlee
http://www.uggaustralia.com/Pr.....=Rosabella
A relative also bought my dad a pair of Ugg slippers a few years back (actual slippers, not boots that happen to look like slippers) and apparently they are super warm & comfortable to wear around the house.
(Oh, and there's also this past blog post to reference.)