  We revisit the tidal stability of extrasolar systems harboring a transiting
planet and demonstrate that, independently of any tidal model, none but one
(HAT-P-2b) of these planets has a tidal equilibrium state, which implies
ultimately a collision of these objects with their host star. Consequently,
conventional circularization and synchronization timescales cannot be defined
because the corresponding states do not represent the endpoint of the tidal
evolution. Using numerical simulations of the coupled tidal equations for the
spin and orbital parameters of each transiting planetary system, we confirm
these predictions and show that the orbital eccentricity and the stellar
obliquity do not follow the usually assumed exponential relaxation but instead
decrease significantly, reaching eventually a zero value, only during the final
runaway merging of the planet with the star. The only characteristic evolution
timescale of {\it all} rotational and orbital parameters is the lifetime of the
system, which crucially depends on the magnitude of tidal dissipation within
the star. These results imply that the nearly circular orbits of transiting
planets and the alignment between the stellar spin axis and the planetary orbit
are unlikely to be due to tidal dissipation. Other dissipative mechanisms, for
instance interactions with the protoplanetary disk, must be invoked to explain
these properties.
