Most warnings and advice goes to doms, almost with the sentiment that all good subs need to do is be willing, or do everything a dom says to be a 'good' sub. Is this true (I hope not...sounds a little boring)?

So, those with a lot of experience in these dynamics: what are the hallmarks of a great sub, and what are rarer things that just make you go 'yep—now that's a great fucking sub'?

Not the things in-scene even, like agreeing to things, or acting sexy, or wearing your favourite lingerie, but the bdsm mechanics stuff that signifies a great sex partner? I'm pretty new to it, and would love to know what to shoot for.

Likewise, do the above answers differ for switchy subs or bratty subs? I'm so curious, so long comments are welcome. :)