  We reassess the structure of the effective action and quantum critical
singularities of two-dimensional Fermi systems characterized by the ordering
wavevector $\vec{Q}= \vec{0}$. By employing infrared cutoffs on all the
massless degrees of freedom, we derive a generalized form of the Hertz action,
which does not suffer from problems of singular effective interactions. We
demonstrate that the Wilsonian momentum-shell renormalization group (RG) theory
capturing the infrared scaling should be formulated keeping $\vec{Q}$ as a
flowing, scale-dependent quantity. At the quantum critical point, scaling
controlled by the dynamical exponent $z=3$ is overshadowed by a broad scaling
regime characterized by a lower value of $z \approx 2$. This in particular
offers an explanation of the results of quantum Monte Carlo simulations
pertinent to the electronic nematic quantum critical point.
