I haven't got much experience with laser collimation. I'm shopping for a laser collimator (simple, slip in), and I have been wondering: how do I know, or how do I test, that the collimator itself is well collimated? I am assuming that for it to work well, the laser collimator tube needs to be ideally co-axial with the laser beam coming out of it. If the beam was off by a small angle, this would affect how you align the secondary mirror (to get the laser spot centered on the primary), and then wouldn't this screw up your telescope's collimation? ... or at least it would affect the alignment of your focussing tube / eyepiece towards w.r.t. the optical axis, if your focusser has such alignment possible.
What experience have you had with laser collimators that do not work well, possibly for this reason that the beam is not co-axial with the tube of the collimator?
Are some brands of laser collimator more carefully built, better aligned than others? They start out pretty cheap, and one would think spending more might get you more quality (but often this is not true).
Does it even matter? Is my thinking incorrect about this?