Not sure who would fall for this kind of scam, but here is a link to show that they do happen:
http://gulfnews.com/xpress/abu-dhabi/ne ... -1.1523051
Beware international teaching scam
Comment
The big red flag is the referral to a specific travel agency and a requirement that the teacher pay the visa fee in advance. If there is a specific agency than its because the IS is paying. If the teacher is doing it and they are paying you can use anyone you want.