reasons for inviting people

The other day we were supposed to have some Americans who are doing a study on tourism in Tunisia staying over for dinner at our place. I was a bit sceptical about that because they had been questioning my friend, who knows quite a bit about the topic, for quite some time and for free too. For some reason or the other research ethics and the equality in the relation between informant and researcher are an important issue to me. So when I heard that apart from talking to them for hours about all kinds of issues related to tourism they were also invited to our home and looking forward to eating Couscous with us I was not too happy. But the invitation was made and therefore things could not be changed without embarrassing one or bouth parties involved. The only thing that was left for me was giving advice to my frined that next time he thinks about it twice befor agreeing to a lengthy interview. He agreed and added that he might ask for money but also he mentioned why he had invited them although he knew that their relationship was quite an unequal one:

because they are ignorant and therefore need to be educated about my
country...

I guess the next time I am invited I will watch out for the real reasons of being invited to somebodys home!