I'm currently looking for a regular Brazilian Portuguese teacher, and there is a LOT of competition which makes it great for me in terms of wealth of choice. In these circumstances one of the things that I can afford to reject based upon, is the quality of sound in the introduction video from the teacher. It is difficult enough to learn a language online, but recording in an echoey room with a very cheap mic or the laptop mic makes it even harder to hear clearly and thus to learn. If you are teaching and are finding you are not getting quite the responses you are looking for, consider investing in a better microphone or ESPECIALLY a little room treatment (things like cheap studio foam or just do the lesson in a room full of soft furnishings to absorb the sound.) Look up "how to sound treatment" to find many inexpensive tips.