Some of the older and perhaps the newer throttle bodies had some sort of an anti-stick (something like teflon) coating to keep oil vapor from forming deposits on the throttle body and air bypass valve. It was recommended not to use carb cleaner or other harsh chemicals on them because they would strip the thin plastic-like coating away. The specific one I'm talking about was the latter year 5.0 mustangs. Starting in 1991 or 92 they had a warning sticker on them not to use these cleaners. The earlier ones would coke up with oil deposits since the crank vent tube went directly in front of the throttle body. This would gum up the throttle blade and allow nastyness to circulate through the air bypass valve, clogging it up and making it respond sluggish, causing a "hunting idle."
Maybe thats why they make a throttle body specific cleaner.