There are two sides to this, aren't there? The question of facilities and that of standards.
On facilities, it is just silly to say that clubs at our level play on parks or at the back of a pub or somewhere. As Brian said, it's only when you get to four divisions below in the Manchester or Cheshire League that you start to get clubs who may play on a railed off pitch in a public recreation area, or at a college, but even there plenty of clubs have private enclosed grounds.
On playing standards , "Sunday League" covers a massive range. Some leading clubs pay their players, I believe, although I am not sure quite how "official" that is. Also, didn't John King spot Mark Maddox playing for A3 in the Liverpool Business Houses Sunday League (I think I have got the club and league right)? Should we have refused him with a patronising sniff of "Sunday League"?