Bad Chinese food
We've been burnt twice on what my mother-in-law memorably referred to as "Brown Goo": bland food in generic cornstarch-thickened brown sauce. Avoid: Ha's, Danville; China Paradise, Blackhawk.
We do now have a short list of recommendations to try, though.
Indian food however remains a mystery: unlike Silicon Valley, there isn't a big Indian population in the East Bay so there aren't many restaurants to choose from. Mexican restaurants are most common (especially out towards Concord, which has a high Hispanic population); and there's a fair number of Thai and Vietnamese restaurants around also.