When you give something, the receiver feels obliged to give back. This is smartly used by many people and living in social set up, we are obliged to give back when we receive something. At times we know that we are falling in the trap and still we can’t do anything because we are taught that taking and not giving back is not socially desirable.
Way out is, either politely and if needed strongly deny the favor so that you don’t have to return the favor. OR when you know that favor was done with the expectation to misuse the social norm of giving back, be brave enough, and simply don’t return the favor.
Sometimes, you have to be smart on how to deal even on the agreeable norms. Not being fooled is ethical. Ethical to your own being and to nature herself.
Think Big. Be Wise.