Okay, so it's not exactly a fashion faux pas. It's more a beauty one but still contributes to your overall style.
There is nothing more gross that seeing someone's glued extensions on the back of their head or the lumps at their scalp. Even worse? When they don't match the colour of the hair which is actually growing from your scalp.
No one ever seems to be happy with what they have. We dye our hair because we hate the colour, we straighten it if we have ringlets and add GHD curls if we have dead straight hair. It's a crime in my books however, to wear tacky hair extensions. If you love the thought of having long hair so much, spend the dosh and get the real deal.