The builder told you correctly, they can be problematic. That said there are basically two opinion groups out there, some say toss them, some say use them. I don't see a noticeable difference either way. The bigger issue these days is leaky floats, even brand new ones can have pin holes in the solder seems, more and more common these days. Another is people buying replacement fuel pumps that look stock but deliver 8-10psi, about twice what a stock needle and seat can handle without blowing open and flooding the bowls.

.02