SKW crews will generally make every effort to get JSer on board (we may have a few bad apples like any other airline). But the vast majority of our airplanes have acars, and you cannot fudge the ZFW with acars.
It's illegal to go if acars does not match the ramp's pax/bag count.
Often the problem is CG...the JSer throws the CG too far forward, but you can't add 400 lbs in the back for balance due to ZFW.