I may be mis-remembering, but I seem to recall that Illustrator was extremely good at being able to micro-position curve anchor points by dragging. It may be since the advent of smart guides, but anchor points in maximum magnification seem to snap to non-descript points - or even move completely when using the combine tool or similar. All snapping is turned off - as are smart guides.
It may well be that I should work on enlarged artwork and then reduce it to the required size, but why should I? Is it a bug?
Any enlightenment would be appreciated