It’s very easy to fall into the trap of thinking that the insulation of the internet allows us to be bitter, snarky, etc., with impunity. Perhaps in an anonymous environment like Slashdot that may be the case, but when all your interaction is tied to your very public identity, as on LinkedIn, guess what? It’s going to be looked at by potential employers.
And who wants to work with someone that is bitter, resentful, depressed, snarky, over-critical, arrogant, whatever?
I’m not saying you have to be all rosy and cheerful all the time, but just think carefully before you let those negative emotions out in public online, especially on a professional networking site like LinkedIn.