Power buffing auto paint - a tool use question

[Bill Houghton]

So, I got a power buffer, like this but cheaper:

to clean off the winter's accumulation of stain from our redwood tree, which had turned the hood on the RV into an abstract of black squiggles on white paint.  While it was a lovely art piece, it failed the wife test, so it was time to get rid of it.

My recollection, from my very brief career as an auto detailer (six months, Fall of 1973), is that the journeymen used an old screwdriver, held parallel to the wool buff, to clean off buildup on the buff.  They sell fancy-dan "cleaning spur" tools, like this:

for the purpose, but the screwdriver seemed to be working well today.  Is the cleaning spur superior enough to spend $10 on it?