  It is shown, that fitting parameters of a $\bar{K}N$ interaction model to
different sets of experimental data can lead to physical conclusions which
might provide a deeper insight into the physics of this multichannel system.
The available experimental data are divided into three parts: the "classical"
set consisting of the low-energy $K^-p$ cross sections and the threshold
branching ratios, the SIDDHARTA $1s$ level shift in kaonic hydrogen and the
CLAS photoproduction data. We have fitted the parameters of the potential to
different combinations of these data. We found, that the two poles
corresponding to the $I=0$ nuclear quasi-bound state ($\Lam$) and to the $K^-p$
$1s$ atomic level seem to resist to their simultaneous reproduction at the
right place, though a more or less satisfactory compromise can be achieved.
Potentials with the $\Lam$ pole pinned down close to the PDG value fail to
reproduce the classical two-body data with an acceptable accuracy. We also
added comments on two papers criticizing the potential used in the fits.

Nuclear Theory