One

You simply don’t have all the information you need.

Two

There is too much information to portray in the required space.

Three

The offer / product has no discernible benefit (in which case, either point it out, or don’t bother stressing about it. Get a plain description done and stop worrying about moving mountains).

Essentially you need to pick your battles, certainly when working in-house. You need to know when to challenge things and when to let things go.

Four

It’s difficult to portray a sentiment / tone / idea with only a few words so make sure that anyone requesting this kind of copy allows enough time. If someone rings you up and says “I just need a couple of quick lines of copy” then alarm bells should start ringing.

Set expectations and allow yourself half a day to investigate and research.