[SCRIPTING] Create object style based on selected object

You can try this. Might want to exclude certain properties that you don't want to carry over. Some won't carry over (ie if they are read only): 

var select = app.selection[0];
var aNewStyle = app.activeDocument.objectStyles.add();
var styleProps = aNewStyle.properties; 
for (var prop in styleProps) {
   if (select.hasOwnProperty(prop)) {
        try {
            aNewStyle[prop] = select[prop];
        } catch(e) {
            //likely a read-only prop
            $.writeln(e);
        }
   }
}
select.appliedObjectStyle = aNewStyle;
//don't know how you want to name it

You've just given a very good description of the best way to create an object style. Object styles are usually applied to text or graphic frames. Apply all the settings you want to use on a particular frame (fill, stroke, text frame options, paragraph styles (often applied with next style), effects, and so on). Then on the Object Styles panel, choose New Object Style... and you've created an object style based on the settings of the selected object. Applying that object style to another frame applies the same attributes.

Is there some reason that this is not working for you?