Short description of error
when you rotate object in for example Y axis and then try to scale it by -1 in Y world axis it takes Y local axis instead of world Y axis. It does not happen while grabbing or rotating- you can grab or rotate in global and local coordinate and have expected result. scale does not work that way.
Exact steps for others to reproduce the error
in attached file
there are 2 boxes rotated in X axis by -30deg. the right one has rotation applied.
try to scale left box in Y world axis by -1. it should be the same when you do it with right box.