I think people worry too much about vinegar infection. It is easy to start vinegar with a good mother of vinegar inoculation and you can make some good vinegar. You can also start bad vinegar by letting fruit fly's get in your must at some point and then letting your finished wine be exposed to air for a long time. But in reality your wine does have to be exposed to air and for a longer period than it will take to go bad due to oxidation. So, unless you are really careless and making really bad wine, it is not going to turn to vinegar even if some fruit fly's get in it.
I have had a few commercial wines turn to vinegar. They were bottles that I had opened drunk some but did not finish the bottle, and then pushed the cork back in the bottle with the cork screw hole in it. Then I put them in my liquor cabinet standing up so the cork dried out. I forgot them for perhaps a year. They turned to very nasty tasting vinegar. If you treat your wines this badly, you may make bad vinegar too.
Ray
