I know from teaching that actors want to act. Even the subtlest actors can do a little too much.
If you think that by threatening me you can get me to do what you want... well, that's where you're right. But - and I am only saying this because I care - there's a lot of decaffeinated brands on the market that are just as tasty as the real thing.
Every time I get a role I think, 'I've actually fooled them again, I can't believe they keep falling for this!'