You can rotate the keyframes in the Graph Editor, all selected at once, or one at a time. You can grab keyframe handles and move them in X and Y, one at a time, or all selected ones. I don’t know of a “Magic Button” to automatically clean the lot in one go, but you might read this thread for some pointers ref the Simplify F-Curves Add-on.
How much do you use the Graph Editor?
Cheers, Clock. 
EDIT:
Two images, before:
After:
