Just say No
I spoke to a foster this afternoon who called to say that someone wanted to adopt one of her cats and take it to China. She was in a tizzy as she said that she didn't want the cat to be taken out of the country. For the first few minutes, I wasn't sure if the cat was with her or had already been adopted out, but it was still in her care.
I said that she could always choose not to give the cat to the adopter. She said the adopter was very insistent. I told her that even if the person was insistent, there was no need to give the cat to him or her - she could just turn them down, because it was HER cat. She wanted to know if the Society could ensure that the adopter would keep her updated and allow her to visit the cat. I told her that she could of course ask to visit the cat because this is between her and the adopter, and ask for photos or whatever she wants as well, but the cat would be out of the country. Unless she is prepared to fly to China, followup visits are going to be a bit tough.
Remember it is absolutely fine to say no if you are in any way uncomfortable or unhappy with an arrangement. Don't adopt a cat out and then worry about it later. If your gut is telling you no, don't be afraid to go with that even if it may offend someone else. You do of course have to bear in mind your circumstances too - as I explained to a foster yesterday, if you can afford to hold the cat as long as it takes (and ideally you really should), then wait for the RIGHT person. Some people cannot - and in that case, the all right person may be the best that they can do.