What the heck is this flavor?

So I'm on my eighth batch or so and have found a distinct "lambic" / caramel/bready twang in my more delicate beers (Blonde, Light Ale, Caramel Cream ale). The taste is noticable after the primary fermentation all the way through to bottle/kegs.
I'm trying to track down the source of the off flavor and need a bit of help with causes/ effects of a few possibilities.

All batches have been extracts.
All batches have been sanitized with iodosphore (sp.?)
All batches have used wyeast smack packs
All batches have fermented between 66 and 72 degrees

Questions: What are the flavors like from: Oxidation, contamination, and the mistical "Extract Twang" ?
Please help, I HATE wasting beer!!!!!

Hey check this place out.... just found it...

http://www.homebrewzone.com/off-flavors.htm

You have to do a better job of explaining the off-flavor.

I'd recommend reading the chapter on off flavors in Palmers book, www.howtobrew.com and narrow it down.

Lambic to me would be sour, but caramel, bready would be a certain type of malt, or yes, just extract twang. Let's narrow this down a bit, and we can pinpoint exactly how to fix your problem.

Are you getting vinegar, acidic? That would be an infection. Sanitation is the obvious issue.