Likewise, devs need to - politely, but firmly - know how to push back on some 'designs'. I push back on bad designs - things that obviously won't be usable on multiple devices, have demonstrably poor UI, etc - when I know that the 'design' was done in a vacuum, without any testing or acknowledgement of web realities.

I've worked some truly awesome design folks over the years, but also had some folks have their 'designer' send me a PSD from themeforest that they went in and added crap to that made it essentially unusable, then charged the client $800 for a $30 theme.