ignoring Dimension leaders...

Hi- I'm sure i'm missing something very simple but I have a thing that
annoys me a little. is there a setting somewhere that makes
dimensions "un snappable"? ex- when placing my dimensions, there are
times when it gets pretty crowded and I accidentally will begin a
dimension on what looks like the endpoint of a line, but in fact it
snaps on the endpoint of a dimension leader instead, which then gives
me the wrong dimension. and to look at it, it does not look like
anything is wrong because the leaders appear to be coming off of the
endpoint or whatever. I know i could increase the gap from where the
leaders/arrows are placed but sometimes it does not matter. I just
wonder why autocad allows dimensions to be, well, dimensioned? that
would be like doing a project and dimensioning from the edge of the
paper to the center of the widget, as if it mattered....