Cropped tops that look like underwear. I don't care how lovely your bare midriff is, I don't want to see it unless you are on the beach, in the gym, running a marathon, or on the dance podium in a nightclub. Anywhere else is just tacky.
Men's trousers that are far too tight and far too short.
Oh, and the wedding dress trend I ABSOLUTELY HATE is that ultra deep cut, sweetheart or V neckline, slashed almost to the belly button then held together with skin toned nylon mesh stitched underneath. Especially if they are beaded or spangled. It makes the bride look like one of the cabaret dancers on a cruise ship, or a like she's in a particularly complicated swimming costume, or like she turned up in something she bought from Ann Summers for her wedding night, but forgot to put her dress on over the top. Yuk.
They are not even very flattering. That very deeply slashed cleavage makes everyone's boobs look like they are being dragged downwards, and it gives the illusion of looking thicker around the waist than you really are.
Or those wedding dresses with bodices that are made of very sheer lace around the midriff bit, so you can see all the seams and the stitching, then you can clearly see the solid bra cups underneath. It doesn't look like a dress. It looks like a bra and a skirt with the top bit missing.