I wouldn't use it. Just order the flux online. Better safe than sorry.

well it kinda worked fine, i used a very minuscule amount.

Just make sure you use some flux remover... :)

plumbing flux is very corrosive and shouldn't be used on electronics.

I’ve got electronics here that plumbers flux was used on them over 15 years ago that still work fine. Flux is corrosive, to your skin, not copper and soldering. If you use it properly that’s all it comes in contact with. Flux is not electrically conductive either.

I've seen stuff to suggest otherwise...

well, i stuck my multimeter pins in a can of flux very close to eachother and it doesnt seem to conduct... it was very close. almost touching. and it was the plumbing flux. so i think the kind i have isnt conductive :) others ight have conductiv properties like sped said.