Teaching sign language ethically
An eyebrow often raises, questioning about a hearing ASL instructor's understanding of the ethical practice, history, culture, and social issues of the Deaf community, when the hearing person teaches ASL, especially in an educational setting and other settings (e.g. a paid position of teaching ASL, running a website, etc.).
A language of our Deaf people is the core of our identity, culture, and pride that we highly value. Where there is language and culture of the people, its history is also signifcant to be aware of.
In our Deaf history, in defense of our language (and modality) and human rights, we have been affected by and have been fighting against hearing-based colonialism, oppression, audism, linguicism, phonocentrism, signoclasm, eugenics, and so on within this hearing or phonocentric society that spans over the past thousands of years. Our language, culture, and history are deeply interweaved.
If you're taking an ASL course taught by a qualified Deaf instructor, you're truly lucky. Trust me. A Deaf instructor not only teaches you ASL, but also they encompass culture, history, Deaf humor, Deafhood, language accent, and all on a cellular level.
A hearing person teaching sign language, especially making profits, is a very sensisitve issue. It represents a hearing privilege, oppression, ignorance, insensitivity, and disrespect (with a very few exceptions, such as a native-ASL coda under special circumstances).
In short, a hearing instructor teaching ASL is an analogue to white people teaching languages and cultures of the First Nations or Native Americans. That's unacceptable. A hearing ASL instructor doesn't get it, no matter how they defend or rationalize. They just don't get it, period. A hearing privilege is part of their package. Interpreting jobs are plenty out there.
"I have a strong reservation about CODAs teaching ASL and Deaf Studies. Their hearing privileges will often jump out and that’s not healthy for any ASL programs."
Hearing people and the native signers do not have the same (signed) language accent.
Avoid cultural appropriation
In the age of globalization, cultural appropriation is common but there are some certain limits or sensitive boundaries everyone must respect. For example, it's greatly disrespectful when white people wear, sell, or culturally appropriate a native tribe's chief headdress. This area, for example, is untouchable.
If this example helps you comprehend the same level of an untouchable area, this parallels to hearing people teaching ASL, especially with making a profit or gaining any non-monetary form. Teaching ASL appropriately and accurately is important to our Deaf community and is deeply tied to our long history.
Baby sign language and the ILY handshape are a few of some examples of cultural appropriation. We are delighted that hearing people are interested in learning about our language and culture as long as their primary purpose is to communicate with Deaf people. But, it's not their place to disseminate misinformation and miseducation. Let qualified Deaf instructors do their jobs.
Ask culturally Deaf people. You might ask interpreters, ASL students, and hearing signers, perhaps out of convenience, curiosity, or proximity. But, don't take them as official information. You might be delightful showing your family members how to sign some ASL signs in private home, on a bus ride, or such, but don't teach online (broadcast) or such. Research further and eventually ask native ASL speakers, Deaf of Deaf families, or such especially Deaf ASL instructors. Further, read materials approved and/or produced by Deaf academia.
Respect our language and culture.
"Hearing friends ask me to perform certain words or phrases in BSL and it makes me uncomfortable, I will not enable parroting of this language without an understanding of the deaf community, I encourage people to learn properly, from a deaf teacher." 
A unspoken rule and ethics in the Deaf world is that teaching sign language in formal and informal settings must be given a priority to Deaf ASL instructors.
Where there is a high discrimination in employment for Deaf people (a high rate of underemployed and unemployed) in North America, a hearing ASL instructor takes away one job less from Deaf instructors who love, respect, and are passionate about their own language, culture, and history. A hearing person can work as an interpreter, a plenty of the opportunities as an interpreter.
An interpreter remains as an interpreter, not teaching ASL. If someone wants an interpreter to formally teach them sign language, hire a Deaf instructor, not the interpreter which is a different skill from teaching the language.
Archer, Alice Archer. "The Shame of hearing privilege." July 20, 2015. http://limpingchicken.com/2015/07/20/alice-archer-my-hearing-shame/
Related posts: qualifications that students look for in ASL instructors.