Many women find themselves perilously perched on the fine line between wearing clothes with sex appeal and clothes that are pure fashion don'ts. See thru clothing has been marketed most often in the form of a blouse or sweater that is made from thin, lightweight fabrics or a loose knit stitch. The problem is that most women don't wear see thru clothing well.
See thru clothing is not designed to be worn alone, however the fashion police could bust many women for doing just that. No matter how incredibly beautiful you might think your bra is, if you can see it, you're wearing the wrong thing. Fashion experts agree that a sexy style requires leaving some things to the imagination. See thru clothing leaves a bit less to the imagination, but shouldn't be worn so that you may as well have nothing on at all.
That's not to say you can never ever wear see thru clothing tastefully. There are many blouses that are designed with sheer sleeves and a sheer back. If the blouse doesn't have a built in camisole or at least an opaque front, you need to wear a camisole under it. And if it's a sheer back top and you can't get away without wearing a bra, don't wear the top. Nothing screams permanent lack of fashion sense louder than a bra strap showing through a woman's top.
Some see thru tops have shelf bras built in and this is a viable option for someone who may be a B cup or smaller, but larger breasted women need bras. This is where the camisole comes into play. A camisole will reduce or eliminate the seams of a bra and will tactfully provide an under layer for a see thru blouse or sweater. Essentially, the rule of thumb for wearing see thru clothing is to never, ever let 'em see your bra.