Well, we only had it happen a few times. Sometimes people stop and ask, but when they don't have a credential it is pretty easy to weed them out.
These lads were a little smarter and answered my questions with half truths when I opened the door.
"Peregrinos?"
"Si, and we can speak English if you want."
(Clue one: Two teen boys hanging around with some local girls, who know we are Americans.)
"We have all the pilgrim equipment as you see."
I let them in and said "May I see your credentials?"
"Well we have one from last year when we walked from Sarria to Santiago, but right now we only have our phone to show you where we have walked."
Phil and Paco come to the entry and begin questioning in both Spanish and English. (Phil is a retired cop and military officer.)
"What do you mean you don't have a credential with you? You told her you were pilgrims" (Paco in Spanish)
"Yes. We are on the GR 10 which is the same as the
Camino de Santiago. The priest at Sarance let us stay. We did not need a credential. We have walked from Pau. (Showing us the phone GPS tracks). Can we buy a credential?"
"I know the priest there and it is not likely he would let you impersonate pilgrims. I am not in charge yet here, but this is only for real pilgrims and not hikers who walked once to Santiago. I would not let you stay."(Paco in Spanish)
"We do have credentials for sale if you are really Pilgrims. How do I know you are not tricking us?" (Me in English, I have a soft spot for stinky boys after having three sons.)
"Yes, we will buy a credential. We have a credit card." (In English)
"No, there are other albergues that accept credit cards, but not this one. There is another one here in town and two in Villanua as well as a Youth hostel." (Phil in English)
"I will run to the ATM and get money. It is only 5 minutes. The other albergue is full and told us to try here." Hmmn do they have a car? No ATM here in our village.
"No, you may not stay here. Lo siento." (Phil in English and Spanish)
With that, Phil showed them out and they left.
(Approximation of the conversation with a lot of hand waving and some begging and shouting, with the aroma of unwashed boy feet permeating the room.)