What do you think of this knit dress?
It does have rather a slimming effect-- I'll give it that much.
On the other hand, the placement of the colorful chevron pattern looks almost like a HUGE tie. . . the cravat-ish thing at her neck is bizarre. . . and her knit ski cap (or toboggan, as we always called them when I was growing up)-- well, it looks like she robbed it off some scruffy fisherman, with little regard to how it might look (especially in combination with this dress).
. . .So I guess it just depends on how important you think it is to look skinny.