I give it in their water every day as well but I still will spray it on them whenever we go somewhere that fleas are a possibility.
We have a friend that we believe has a flea problem in her home. Before we knew about the ACV we got a bad infestation. We got it cleared up and and then ended up seeing our friend. Started finding fleas again. We were not happy. Every time we got them cleared up and then went to see her we would find fleas on them. So now every time we see her they are sprayed down. We have not had anymore problems since
They smell like a big salad but I would prefer that then fleas :D
I honestly don't know if it will work for every pet but it works for ours