What do heavy-light ($Q\bar{q}$) quark systems tell us about QCD vacuum properties?

Arguments in favor of a large magnitude ( at least two- three times bigger than its factorized value) of the mixed vacuum condensate $ \la \bar{q}G_{\mu\nu}^a G_{\mu\nu}^a q \ra$ are given. The analysis is based on the strict inequalities which follow from the QCD sum rules method and on very plausible phenomenological assumptions like $m_{B_s}>m_{B_u}$ for the few lowest exited $Q\bar{q}$ states in a heavy quark limit $m_Q\to \mathrm{\infty }$. The same arguments show the suppression of the $SU(3)$ symmetry breaking effects for vacuum condensates when the additional gluon fields are included.