  We reanalyze critically the generalized factorization hypothesis in
non-leptonic two-body B-decays discussed recently by several authors. In
particular we address the determination of the factorization scale $\mu_f$ and
of the non-perturbative parameters $\xi^{NF}_1 (m_b)$ and $\xi^{NF}_2 (m_b)$
which are supposed to measure non-factorizable contributions to hadronic matrix
elements with $\xi^{NF}_i (\mu_f) = 0$. We emphasize that both $\mu_f$ and
$\xi^{NF}_i (m_b)$ are renormalization scheme dependent and we demonstrate
analytically and numerically that for any chosen scale $\mu_f=\ord(m_b)$ it is
possible to find a renormalization scheme for which $\xi^{NF}_1 (\mu_f) =
\xi^{NF}_2 (\mu_f)=0$. The existing data indicate that such "factorization
schemes" differ from the commonly used schemes NDR and HV. Similarly we point
out that the recent extractions of the effective number of colours $N^{eff}$
from two-body non-leptonic B-decays while $\mu$ and renormalization scheme
independent suffer from gauge dependences and infrared dependences.
