Thanks gents. Sounds like I'm hopefully on the right track.
I don't usually remove the posts, that's a new extra sanitation step that I've been taking.
The bottling process is pretty much the same for my kegging: in fact, I'll bottle a dozen bottles using the same tube, just hooked up to a wand, then when done bottling the few bottles that I want to do, I'll hook up to the tube to a ball lock and hook it up to the keg and keg away. I've switched between using the ball lock or just letting the tube dangle inside the co2-purged keg with the lid removed, both have had issues, so I don't think it's the ball lock, especially since it's rinsed and dunked in star-san even if I look at it wrong.
It's been several kegs, which also contributes to my overall confusion: How does an infection go from one keg to another? I have about 13 kegs in total, and I haven't tracked which ones have had infections and which ones haven't. This I will start doing now that I've determined it's not just a couple of funked batches and there's a problem somewhere.
I think it's possible I had a batch of bad beer in the carboy that went bad (that has since been fully sanitized.) And between the couple of batches that I've done that have gotten funked, they were hooked up to the kegerator, then later non-infected batches being hooked up to it that probably had some infected beer left in the line, etc, I can make loose enough connections to see how it happened and spread across multiple kegs, while not necessarily fully infecting that keg, but having enough of the bacteria left that survived the iodaphore that when I did keg the next batch, whammo. Which is one of the reasons I'm going crazy with the cleaning/sanitation regimen. Whenever a keg is now emptied, before I hook up the new one, clean the old with PBW, run the PBW through *both* beer lines (I have a dual faucet) just in case, rinse, run star-san through, keep star-san in the keg ready for the next batch.
If this persists, I think changing the gaskets in addition to everything else will be the next step. Though I think the few minutes the gaskets spend in with the barely boiling water should kill most things, and whatever does survive, the spritz of star-san should take care of the rest. But if this doesn't get better, that will be the next step.. quite possibly running boiling water through all of my kegs as well. Chemicals can't get everywhere: heat can. I just hope I don't have to go to that level.
And yeah, when I do pour the beer out, it'll be into the mulch pile which will feed my hops the next year, so the circle of beer life will continue