Dave, do you use iodophor or bleach occassionally for sanitizing? After Mark's illustration that Starsan doesn't work on all spoilers, I've been more open to iodophor use. I'm still leary of using bleach on my plastics and hoses, but it sure is an effective sanitizer. Occassional Hose replacement is probably still a good policy.
I haven't used bleach for many many years. I agree, it would probably be a good idea to switch sanitizers more often. This advice applies to all homebrewers of course, not just me or people who are having problems. Maybe every 5 or 6 batches or so we should be switching it up. And the hose thing, definitely more often than I've been doing (I think it's been about 5 years now).
I've been considering building a "hose sanitizer" using my sump pump to recirculate iodophor through various diameters of tubing I use for transfers. Ideally, I'd like to find a "stepped barb" so I could just slip the tubing over the end and let it recirc for a few minutes, then switch ends since the end on the barb probably wouldn't get much action.
My goal is not to avoid replacing tubing but to get a few more uses out of it. Right now with all the various tubing I use for racking, keg to keg transfers, etc, I find that I'm constantly throwing away tubing that I've used once or twice because I can't remember the vintage or it just doesn't "look right". I'm probably overly paranoid about this, but given that tubing is difficult to clean, sanitize and dry thoroughly, it seems way too easy to get mold or wild yeast going in there (which are less likely to be killed by StarSan).