Will Uracil-N-Glycosylase (UNG) completely remove contaminating amplicons when using QuantiTect +UNG Kits?

This depends on the amount of contaminating amplicon. If the contamination is high (e.g., 10e6 copies), then there will still be traces of amplicon remaining. However, we expect a reduction by a factor of around 1000 using QuantiTect +UNG Kits (i.e., after UNG pretreatment, only 0.1% of the initial contamination will still be present in the reaction).