I wish I had an example for you to hear, because once you actually hear it pronounced that way, it will be very clear to you. Maybe once my computer stops being broken, I will find try and find/make a recording of it. It sounds closer to, "bi-yit" then the harsh sound of "beet."
In regards to 'standard' English and accents, everybody, and that is EVERYBODY speaks with some accent or another. There are just certain accents and dialects that are negatively stigmatized, hence people try to change their accent or dialect to a less stigmatized one. An unstigmatized dialect is also called "prestige." These prestige dialects are often what is spoken by the social class that has the most money, influence, power, etc. The idea of a 'proper' way to speak in America has arisen also through the media, as they try to speak a very bland standard English.