I've never heard an American spell out "etc.", correctly or not, in conversation; I'm having trouble believing that doing so, much less a particular incorrect way of doing it, is common generally among "Americans", though there may be some narrower regional or other subculture in which it is common.
I am American and say "ee tee cee" for /etc.. but this could possibly be because I taught myself computer science online when I was a kid and so never heard people say many of the terms out loud.
