I've had a few "infections", however, I know where mine come from and how to avoid them. Most of the "infection" posting I've seen has to do with suspecting contaminated equipment, I've NEVER had an "infection" caused by unclean equipment and I use all the same equipment for sours as I do for conventional beers.(Disclaimer: See paragraph two)
My "infecting" yeast/bacterium comes from an area, not equipment, it is my cellar, I'd suggest that anyone with an "infection" that they can't seem to eradicate take a look at where they are fermenting, or brewing, or chilling and consider changing their location. I'm not saying an infection CAN'T come from contaminated equipment, I do however think that if your equipment is contaminated, it had to get that way from something in the AREA that you are brewing, chilling, fermenting in, correct?
Furthermore, I'd suggest that if one does get an "infection", instead of freaking out and throwing out all that hard work, why not roll with it. Get yourself a sanke of some sort, set it up with an airlock and throw the "infected" brew in there and experiment. If you get another "infected" brew while you're trying to figure out where the "infection" is originating, throw that in the sanke with the other one, and experiment.
Why is "infection" always seen in "quotes" in my little schpeel here, it is because ALL beer had to be "infected" to be turned into beer, some beers happen to be "infected" by saccharomyces of some sort, some from brettanomyces and/or pedioccocus and/or lactobacilus or other yeast/bacterium. They are all beers and some peoples don't like some beers, some peoples are not used to some beers or haven't sampled some beers. All people need to realize that it is VERY unlikely that anything can live in beer that can harm you.
Brew on my friends