  Recent experimental signals have led to a revival of tetraquarks, the
hypothetical $q^2\bar{q}^2$ hadronic states proposed by Jaffe in 1976 to
explain the light scalar mesons. Mesonic structures with exotic quantum numbers
have indeed been observed recently, though a controversy persists whether these
are true resonances and not merely kinematical threshold enhancements, or
otherwise states not of a true $q^2\bar{q}^2$ nature. Moreover, puzzling
non-exotic mesons are also often claimed to have a tetraquark configuration.
However, the corresponding model calculations are practically always carried
out in pure and static bound-state approaches, ignoring completely the coupling
to asymptotic two-meson states and unitarity, especially the dynamical effects
thereof. In this short paper we argue that such static predictions of real
tetraquark masses are highly unreliable and provide little evidence of the very
existence of such states.
