Most of the complaints against her are that she's a bitch, or that she's a brat.
These statements tend to ignore the far more aggressively bitch behaviour of another HM. As for being a brat, hell even Mark was more of a brat, how many foot stamping, storming off moments did he have? Remember him throwing a wobbly over having no hair straighteners once or twice?
Once those complaints are dealt with people start complaining about her being boring, in a house were Ash has existed. But you then have to ask, if she is so boring, why so many threads and posts about her?
So then people resort to making fun of her face, or her appearance...and at that point...
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“I'll be more enthusiastic about encouraging thinking outside the box when there's evidence of any thinking going on inside it.”
― Terry Pratchett