Right I know for a fact that the GNR were stopping people coming out of Baptista supermarket in Luz today and asking to see their receipts.

NUTS

They do not have the authority to do this, it has been well publicised.
There also has to be a representative of the tax authorities present.
Was it a check on the store rather than the customers if it actually happened.
Not once in the last 4 weeks when shopping in most of the major supermarkets or numerous shops, meals out coffees etc were we asked if we wanted a factura or saw anyone being stopped by the authorities to check to see if they had one.

I am not sure what you mean here. If the GNR do not have the authority to stop people and ask for their receipts it should not make a blind bit of difference who else is there.
Personally even if they don't have the authority to stop me and ask I'll show them mine before they show me their's.

The tax authorities ( AT ) have to be present during an inspection of a business to ensure that it is following the procedures.The GNR are not part of the inspection process.
Customers are not required to ask for a full factura with NIF no unless they want to use it to reclaim part of the IVA.

On the 22.02.2013 during the News on TVI24 the Portuguese Min of Justice a Sra Paula Teixeira when asked about the problems off the PSP/GNR stopping people & requesting to have sight off the Fatura stated.

"Ninguém é obrigado a provar que pediu"

"No one is required to prove so when asked"
(this is a near as I can get)

She also went on to stated
"Theres a communication problem over this matter"

And to add more confusion a high ranked Advogado on another TV station when asked to give his opinion on this said "Under PT Law to legally do so the GNR/PSP are required to have a Search Warrent at hand "

Yet another problem caused by those in power not using there brain !!

thanks

They don't have authority but they were asking clients as they were leaving. You really think a normal person is going to say no to the police when they can slap some fine on you, when most people here are struggling to survive?

They cannot slap a fine on you as there has been no offence.

My neighbour is a GNR Commander, he doesn't speak any English but his wife does, at my request she asked him about this practice, his reply, RUBBISH!

No communication problem there then!