Its great being a bloke.....we all are problem solvers and go straight into solution mode. I do it all the time too.
In this instance, I suspect the answer might lie in knowing more about your brewing / fermenting routine. Phenols are not always caused by infections, and in your case you might change you sanitisation routine and still have the off flavour. Something to consider. You say every 3 or 4 brews the flavour occurs. Do you always use the same yeasts? Go back through your records and have a look at your ingredients. Is there a common ingredient in the brew on the off flavoured beers? Did you change you sanitisation technique? How old is your fermenter, is it plastic or stainless? Plastic fermenters can hide nasties no matter how clean you are, but especially if it has scratches.
BTW, Nick the Knife nailed it when he said that common household bleach when mixed with vinegar is a killer. It sure is, one of the best out there but because it is cheap I think we overlook it. Bleach contains available chlorine which is present in solution in the form of sodium hypochlorite and hypochlorous acid. Hypochlorous acid is a powerful germ-killing agent which kills bacteria, yeasts, moulds and many viruses. I only use it if I have a concern about the cleanliness of something, and then only when I can be sure the item will be totally dry before I use it. Only small amounts of chlorine can create chlorophenols. Maybe you can mix up the fermenter full and soak it for a day or two then put it out in full sun. The sun is also a great assistant.
Last thing from me. Pull apart your tap if possible. Otherwise, soak it in a small jar with your chosen sanitiser.