I have never heard or seen anyone put used race spark plugs in a carb. booster at the drag races, never
Let alone on top of a throttle body
I have broken the porclyn on plugs and not known it until later, I have also installed loose spark plugs boots thinking they where on all the way until they fell off
If you race long enough you will make a mistake or two and break parts
I run air cleaners also so maybe that's just me