Sorry then, you are going to be surprised! IIRC Lady Campanula highlighted this issue on PBO not long ago and YM are about to run a campaign on it, kicked off in the June issue. Many builders are using brass skin fittings and seacocks because the guidelines say they only have to last for five years.
Examples of dezincification can be seen on my website at http://coxengineering.co.uk/BandB.aspx
I would'nt touch such a builder with a barge pole.That goes against everything I have learnt as an engineer & someone that is interested in a good quality product!