Can I use these two sentences interchangeably?

[cubezero3]

Crowded shops are a happy hunting ground for pick-pockets.

Crowded shops are happy hunting grounds for pick pockets.

If not, could you please give me a background in which only one of the two sentences is allowed to be used.

Many thanks

Richard

[bhaisahab]

If not, could you please give me a background in which only one of the two sentences is allowed to be used.

Many thanks

Richard

A crowded shop is a happy hunting ground for pick-pockets.

Crowded shops are happy hunting grounds for pick pockets.

[Rover_KE]

'. . . for pickpockets.'

[cubezero3]

I referred to my A Dictionary of Modern English Usage again, and this time I realised Mr. H.W.Fowler actually intends to say it is a blunder that people say The wages of sin is death.

I'd like to know if there're any cases in which only one of the two sentences is proper.

Many thanks

Richard