Essential job skills: telepathy and mime

My gym has the peculiar policy of showing, on four silent TV screens, four different channels, few of which can be appreciated without sound. (You can always listen in on your own headphones, but really, who bothers?) Occasionally, the news channels will have subtitles turned on, so you get to read - a minute or so delayed - a mistyped and frequently misheard version of the news.

But far more amusing is the blonde woman who delivers Hollyoaks dialogue in sign language. (This is a special perk of going to gym on weekend mornings.) Half of the signing seems to consist of elaborately overacted facial expressions, which makes a sort of sense, since the deaf viewer is obviously so busy trying to see the signed dialogue, they can't be watching the actors as well. Blondie has to give double value; and she does, believe me, she does. Of course, when there's a quiet moment (cut to someone sleeping...) she turns to watch the action, and has the tough job of looking interested but not distracting the viewer. Seems to chew her lip a lot - I'm sure she shouldn't be doing that. Then leaps back into action like an Italian, talking with hands and very, very mobile face.

Which led me to think of Joey Lucas in the West Wing - who is really a double character: Joey plus interpreter. The interpreter is marvellous. When Joey's angry, he has to yell. When she's flirty, he sounds coy. And he does this all super-fluently, at speed, without allowing the conversation to pause; although very occasionally he does insert himself into the interaction ("No, that was me thanking you,"), which is terribly confusing.

But what I want to know is, are real-life deaf interpreters this skilled? Can they really deliver real-time translations, complete with appropriate tone of voice, and without stopping to go, "Hold on, what was that last bit?" or "Can you spell that?" Or are they more like the news subtitle people, who provide literally minutes of entertainment for me at work?