Bass runs are all based on some type of scale. I would say the most common runs would be pentatonic runs. A quick example of a bass run played fast would be
H H H
G-------------------------7----------------------------------------
D------------------7---------9--------------------------------------
A--------5--7/-9------9-----------------------------------------------
E-----/7------------------------------------------------------------
The / stand for slide, the "H" stand for hammer. This is a basic minor pentatonic run. It depends on what key the song is in that usually determans what scale, or mode you are going to make a run on.
Gouche for example might use a modal run and it might look something like this:
G--------14--14\--13---------------------------------------------------
D--/16----------------14------------------------------------------------
A-------------------------14--12\--11-----------------------------------
E---------------------------------------12-------------------------------
B--------------------------------------------12\--11\--10----------------
This starts on major and end on the minor 3rd, but it's utilizing the 5th mode (mixolydian) and the 1st mode (Ionian)
It may sound confusing, but once you learn your modes, and your basic pentatonic scales it will become clearer. If you have any questions feel free to ask.
