Here are two that annoy me:
1) Never knowingly undersold - John Lewis.
Firstly, what the fuck does it even mean?! Assuming it means /you won't find this stuff cheaper anywhere else/, that's ridiculous on twwo fronts. Firstly, because John Lewis/Waitrose is *known* for being quite premium/expensive, so you are quite likely to find the stuff cheaper somewhere else; and secondly because it infers that ehy are sometimes unknowingly undersold, which doesn't show much faith in their claim. Unless i've completely mis-interprested what it means, which is possible of course. But even then, it's their fault for a having a shit, ambiguous slogan.
2) Solutionism: the new optimism - Dow Chemical Company.
Seen this around quite a lot lately on the side of taxis. It's ridiculous, and I can't believe such a major company signed it off. It just sounds like something that came out of a Thick Of It style brainstorm. Embarrassingly awful.