When I respond via email to an international teaching positi...

Yes it is a huge problem practiced by overseas school, especially schools in China and dodgy Chinese teacher recruitment agencies. They ask for scans of your passport, certificates etc to a point that they virtually have your entire idenity. I look at the situation this way and I believe our respective governments share my views. If a person asked me should I send scans of my passport, a photo of me, scans of my qualifications etc to someone online that I do not even really know, of course I would advise that person to " just send your C.V as it contains all the information that they as a potential employer need to know". If offered a job and a visa application process is required then you can do this in person in conjunction with the employer once you take up or accept a contractual offer of employment.
Richard Haberkost.

I have been teaching in China for more than 7 years and it is a BIG problem that most new teachers perpetuate by not using common sense. They ask for a scan of your passport but they do NOT need it! Why you ask? Because the school itself only needs it if you are to be hired by the company. So any time a recruiter asks for a passport photo I either decline stating that to protect my privacy I will only allow my sensitive information out 1. in person or 2. via a fax - ONLY WHEN READY TO SIGN THE CONTRACT. Most don´t have a problem with that. If they want proof of my citizenship then I will send them a copy of my passport with everything concealed but my picture, my name and my citizenship. But most don´t ask for it. Also on any certificates, diplomas or other sensitive items I make sure to either watermark them or write "Sample for employment only" over any seals, my middle name, and dates. You can also get away with not posting your telephone number if it becomes a bother. Here in China they can sell phone numbers to contractors (like sex phone numbers or out of country scams), so when you call the number back there is a large charge that you cannot fight...since you yourself called the number back.

I think, for China especially, and I have no reason to doubt that it would not be the same for other hiring locations, that a copy of the passport information page is way of checking confirming name, date of birth, appearance and ... skin tone. I have no qualms about sending it to a potential employer, but I do agree with other posters, that I would not send it to ANY agent.

Is there a best place to be a teacher of adults? I have experience in K-12, but I would like to focus on teaching adults, who are trying to get ahead financially by teaching English.

...who are trying to get ahead financially, by learning English.

ooops.

Lesley, I have given scan capy of my passport and it does not hurt you when you do that. Alot of the employers want to make sure your a US citizen.

I agree with both Roberta and Richard. When responding to a job posting before a final contract is offered, it is not necessary to send a scan of your passport. And as Roberta stated, you can always conceal the sensitive information. William may not have had problems in the past with scanning his passport, but that´s not to say he will not have problems in the future.

Here’s what I have done: I’ve scanned my passport, and then using photoshop, removed my passport number. But what I think they’re really interested in is seeing your date of birth and your photo (unfortunately, a lot of offers are contingent on your race and your general appearance).