I reckon I'm pretty relaxed about bottle cleaning compared to the elaborate practices of some, but I don't believe I've ever had an issue with infected bottles. I think if you start off with some manky old bottles that have been left for ages, you're on a hiding to nothing. 90% of my bottles have come from beer I've bought in the shop. For me, the moat important thing is to rinse out bottles as soon as you've poured them. I do that, and leave a couples of inches in water in them overnight. Then wash them in the morning (with ordinary washing-up liquid), but of course making certain all suds are thoroughly removed, before dosing them with VWP, and again rinsing out thoroughly with water. I don't put foil over the tops, or anything like that, but they are put away, and get another sluice and soak and rinse with VWP before re-use.