Red resin in-between closely spaced PCB pads
The 3-dot sets between some of the closer pads is a fairly routine fix for when wave soldering can create a short (it acts in a similar way to the solder resist mask).
When I worked in contract manufacturing, we often used this trick to deal with cases where the PCB wasn't really designed for wave solder manufacture. The majority of these dot groups will be in the same orientation, as bridges will generally be seen in the same direction as the board passes over the wave.