Android Studio and JAVA_HOME

There are plenty of instances on the web of people talking about tweaking JAVA_HOME to get Android Studio working. Now, most of those start to point at magic details like trailing slashes or not, running as Administrator or not. This is an example. I don't claim to have the full truth, but the error message about JAVA_HOME and JDK_HOME can be misleading. Android Studio will, according to procmon logs, look at "HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Development Kit" before it considers the environment variables. The vestiges of a now removed JDK setup will make Android Studio fail, no matter what you put in JAVA_HOME. At least, that was the cause for me. The program will look a the 1.6 entry first, so if you install a fresh 1.7 or 1.8 and have a bogus old 1.6 entry, you get the error.