Idle sound

It's both!
If it's too lumpy to idle at 650, as in it want's to stall, then you have to crank it up. maybe it will stay running at 700, maybe not. Keep cranking it up til it stays running. Along the way the T-port sync will get screwed up so then the idle-speed will have to be re-adjusted with idle-air bypass and idle timing. Then the idle will smooth out, so maybe now you can slow it down some. But there is a point when it becomes too slow again; maybe you got no oil-pressure at 500rpm, or maybe the cam drops a lobe or two or three,idling down there with insufficient oil-splash and massive spring pressures.. Too slow is not the way to make a lumpy sound.Besides everybody will know what game you are playing. I watch out for guys who have too smooth an idle but it might be 800. See they could be hiding their cam.....and know a bit about tuning. And if they are sharp that way, maybe they are sharp in other ways too. I might not want to find out!
But if they are idling at over 1000 and lumpy, They are waaaay over my league.I am just going to tippy-toe on by.....Don't pay me no-never-mind, I'm just sliding on thru...Look the other way....Where are my cheap sunglasses?