I thought this too, until I researched the issue. Turns out, BHO's use of vacation time is only average as far as modern US Presidents go. Since the 1970s, the US President who took the least vacation time was Clinton, followed by Carter. The worst? George Bush.
And neither of them really are off work when vacationing. I won't hold this against Bush, Obama, et al. There's plenty of other substantive criticisms of each to go around without this rhetoric.
My word? Fraud.
I mean, even the liberals aren't happy with him.