Originally Posted By: AusMac
One cannot accidentally tape over store bought cassettes as they have tabs that prevent it. One needs to break the tabs out if one wants to record over it.

Other way around: if there is no tab, you can't record. The store-bought album cassettes just have an indentation -- if you want to tape over them, the easiest way is to put a piece of scotch tape over the indentation and you're good to go ;-)