I am a computer scientist from Nigeria. I am interested in attending your conference. I come from a very poor university and I am in need of funds and/or please write me a letter for visa.They play to our vanity and our desire for diversity. Wow, Africans interested in computational complexity! Don't be fooled, in nearly every case they have no interest in computer science, they just want an easy way to come to Europe, the US or Canada.
There is that small chance a poor African student really is interested in complexity so I typically reply to such letters by
Thank you for your interest in our conference. Please send us your latest CV and a statement explaining your reasons for attending the meeting and we will be happy to consider your request.In every case I have never heard from the letter writer again.