anyone heard of a solution of ACV diluted with COOLED boiled water as a cleaner for a dirty ear?

Yes, I've heard of it, although not used it. Have you looked on their website? 

http://www.apple-cider-vinegar-benefits.com/

I use it in the blended veggies I do for my two, amongst other things, it promotes healthy joints. 

Saw somewhere and cannot remember where it was that it was useful for cleaning ears if there was a yeast infection.  Works on the principle that vinegar is acid and yeast cannot live in an acid enviornment.   You would have to be careful with the dilution for the ears, they are very sensitive, would not want to get it wrong and do any damage.

http://www.dog-breeders-net.com/ciderapplevinegar.htm

This site might help. I use ACV for lots of things since I learnt it was a natural anti-bacterial product.

I note this site says though, not to use ACV if there is a chronic yeast infection.

Any chronic condition most probably needs further investigaion by a vet.

Have used it once on one of my dogs, but it did not help, so had to go the vet and the medication that they prescribed cleared it completely, but we had to use a long course, but to be fair she had other underlying health problems.