Being aware of how clothes fit us from multiple angles is always an important thing: our bodies are not one-dimensional, so something that looks good from the front may not do so from the side, the back, or even more crucially, from an angle. This is all the more key for women with shorter legs, whose bottoms and thighs often appear to be 'in the wrong place' and multi-angle mirrors are a super useful tool to keep an eye on this.
Some shops cater for this very well and fit their changing rooms with fold-out mirrors or simply have mirrors on all sides of the cubicle. They are at first really scary - I will not lie, I have had several breakdown moments of 'I never realized I look this weird/awful in this outfit from the back/side!' in such fitting rooms -, but arm yourself with some courage and make the most of these: even to have a 3D look of existing outfits or to doublecheck items bought in other shops with 'normal' mirrors. They will teach you a lot about how your body looks when you move, put your weight on one leg, or just stand in one place but are viewed from an angle. And awareness of this can come in very handy when learning to dress yourself.
Consider the following images that highlight how different garments can look from different angles:
Kaley Cuoco's jumpsuit looks flattering from the front - less so from the side:
Rachel Bilson's dress is a hit from the front - but viewed at an angle, its ruffles oddly enlarge her bottom:
Kate Hudson looks gorgeous from the side in her leather mini but from the front the skirt sits way too low:
Olivia Wilde in a fitted sheath midi - stunning from the front, short-legged from the side:
Another Olivia example, this time with a too-body-con dress - all right from the front, less so from the side:
And finally Rachel Bilson again, in an almost-great fishtail skirt: