I’m left-handed and I use both mouse (on the left side) and the touchpad. So I always change the mouse settings as per left-handed people.
In doing this, also the first and third button on the touchpad are swapped and tapping no longer works as expected (because is mapped to third button click).
This is a little frustrating mostly if you (as I do) prefer tapping for both click and for drag and drop. To resolve this issue you have play a little with Synaptics configuration and Gnome Sessions.