"This pair of pants isn't comfortable."
Dou's sentence is absolutely fine and not at all "inaccurate". A native speaker would no more think it means the pants are unwell than a native English speaker would think "the pants are uncomfortable" means the pants themselves feel awkward or out of sorts. I hear "不舒服" used all the time in this context. That said, your sentence is also fine and IF NEEDED would add clarity; but for this situation, I prefer the simple, concise approach of Duo's sentence.