Of course you can - with the result of WD40 all over the insides of the mouse.
Where will all the excess oil go?
To the bottom of the mouse - spill over the pcb and down to the sensor area underneath.
It's everyones own choice how to mend this issue.
I like my mouse pad nice and clean - free of oil which is why I chose only to apply a few drops in the actual mechanism (left side)
However if you do choose the hit'n'miss WD40 method, there is no need to do it on the right side of the mouse - nothing to lubricate on that side.