The old adage of "If everywhere you go smells like shit then check your shoe" applies here. That's not to say you couldn't have worked at 3 actually bad companies that you should have left but it's at least a warning flag. I've had people with short job tenures back-to-back explain the reasoning and I've been perfectly satisfied with it but I've also had people give me reasons that sound very fake. Interestingly, the people that come across as "fake" are also the ones that give off a slight whiff of "I'm better than this job" or "This is only a stepping stone for me". Those things can both be true but if can't at least pretend to care then I'm not interested.