From my experience so far , sometimes. This has happened to me a few times with ABB, TD and AWW. I have grown these strains more than twice and two at a time per grow (always get 1 pheno). Seems like the taste and smell isnt quite there compared to non phenos, more of a chemical smell which tastes of nothing.
ABB pheno was as potent as the non pheno, same with the AWW but the TD had a slight difference. Seems like the pheno was weaker than the non pheno but just by a little maybe 2%.