I would never tell someone who is designing a sweater how she should proceed unless she asked my opinion. Even if her knitting project looked like a giant barf-covered hairball, I would say, "It's Lovely."
From an Empirical point of view, my words would be a lie.
From an Aristotelian point of view, which suggests that truth is always a negotiation between the speaker, audience, and message of a given rhetorical situation, my words would not be a lie.
Because I (the speaker) would find it lovely that the knitter (my audience) would be willing to share their knitting with a total stranger.
No one should negatively comment on a unknown knitter's WIP unless they're prepared to be proven wrong in their opinion by the utter awesomeness that the project will eventually become.