Homebrew PCBs

You folks aren't making this easy for me...  ;-)

One thing I noticed about my current no-clean is that the residue has
(relatively) low resistance.  If I have a 25 mil gap between power and
ground, an inch of that results in 330k between them.  I end up
scraping between traces to get the hardened residue off.

I wonder if a waterpik would be enough to get those hard-to-reach
places that make people avoid water soluble flux?  I do have some QFNs
in my current project...