Does This Make Me Look Fat?
1) The wrong silhouette, or shapeless altogether? See A Pre-School Geometry Lesson.
2) Too small? See Would You Like Another Roll ... .
3) Put together in such a way that it creates a focal point where you would rather not have one? Like the wannabe glamourous young lady in black pants and black sweater, swath of white lace encircling her hips & derriere?
(A friend of mine used one of these long shirts with the lace hem to create a much more flattering look: matching the lace to the color of her skirt, she created the effect of a coordinating lace belt, and wore a contrasting top over.)
If creating a slimmer appearance is your foremost fashion concern, the book Does This Make Me Look Fat?, by Leah Feldon, may be worth investing in. Read a lengthy excerpt at her website.