A director friend that I'd known when we were both young and learning the business used to have long arguments with me into the night about what was the difference between good acting and bad acting. It is a favorite subject for those in the dramatic arts, made the more favorite because there is, and there never will be, an answer for it. We certainly never arrived at an agreement.
When I worked with my director friend almost a decade later, on his first feature-length film back in 2000, the subject happened to come up. I remember that he sighed, looked exhausted and answered, "An actor that shows up."
A great reality of the business is that actors who reliably do the work, who are easy to get along with and who have lives without a lot of drama, get parts if they can say the words in the right order. Kevin Smith is always happy to work with Ben Affleck and Tim Burton will always work with Johnny Depp. Sydney Pollack wanted Meryl Streep, John Carpenter wanted Kurt Russell, Billy Wilder wanted Jack Lemmon and John Ford wanted John Wayne. People can argue about whether those people were great actors, but the directors knew the people they wanted to work with, to make the projects they wanted to make.
There's nothing worse than an actor that will throw fits, demand excessive treatment, fail to arrive for work with a clear head, refuse to work affably with the cast or preen themselves with a belief of infallibility. You want to know why Keanu Reeves gets parts when everyone thinks he's a bad actor? He works. He'll get dirty. He doesn't drive up the length of the shoot and he doesn't make the shoot run overbudget. He looks happy when he's supposed to look happy and he looks angry when he's supposed to look angry. For most any director in the world, that's more than enough.
Want to know why Tim Roth's career didn't take off? One guess.
As a player or as a DM, when I sit down at a table to play, there's only one thing I truly ask for: to play with people who want to play the game. Not people who want to play the look-at-me gambit, not the people for whom everything is a pissing contest, not the chatterers, not the mopers, not the wanderers from the table, not the chewers, not the ones who can't remember the rules, not those that come cause they're attached to their partners, not the doodlers, nor the lawyers, nor the peevish infants who screech their indignation, not the ones who can't bear to die, not the ones who can't bother to try, not the ones who must be poked to roll dice, who have to be told their gained experience three times, or those who want to pitch their own world, or those who pitch a different game's rules at the table, or those who play this game because they can't find someone to play the other game.
No, the player I want to play with isn't the brilliant one that solves puzzles, nor the clever one that talks in thirty accents, nor the player whose character sheet is a ninety-page tome, nor even the lover of fun.
The player I want to play with is the one that, whatever I tell them, answers back as a person immersed in the game. They're too busy thinking about how to deal with the enormous bear that's just burst through the innkeeper's front door to be concerned with things like characterization, the bear's probable hit points, it's memorized armor class or whether a bear's strength is sufficient to break down a reinforced door. No, what they are is scared. It's a big, scary bear, it's a threat to their life and they are thinking, OH MY GOD, IT'S A HUGE BEAR! WHAT'LL WE DO?!
That is, they are there. Present. Brains functioning in relationship to what's going on. Focused on getting all they can out of it. Emotionally invested. Pick your description. The long and the short of it is that a player like this - whether you are the player's compatriot or the DM - is such a thorough pleasure to play with that you don't give a rat's dinner what sort of brilliant thespian he is at the table. It matters not a mook's wit whether they're behaving in accordance with their past or in accordance with the bar code on their cherished twinkies. Jeb may not have an education, he may be an out-of-work roofer, he might be a wife-killing banker ... but when he's at my table, screaming that "We've got to get out of this place or we're all goners!" he is the most brilliant, slashing bloody bastard that ever girded on a d20.
He's always welcome at my table.