It could have been a brilliant career.

While some people might accuse me of being cold and elitist, there are certain written grammatical atrocities that make me wince. For instance, the improper use of several words: they're, their, and there (and there's and theirs for that matter). You may be thinking, "Who the hell gets those three confused?" Who cares? On with my point...

They're:
This is only to be used in the case of a conjunction the word they and are. So, if you can break the two words out, use they're. For instance:
They're expecting she'll do Stevie Wonder impersonations all night.

Say you're referring to that same group, only in the past tense. Use the two words separately and spare your reader the confusion:
They were expecting her to do Stevie Wonder impersonations all night, but realized she was more interested in visiting with the cat.

There:
For the sake of ease and clarity, let's just say that there should be used to 1. refer to something that is off in the distance or 2. to establish a beginning for your sentence.
Example 1- It's over there, you ghastly beast.
Example 2-There once was a man from Nantucket...

Their:
If it belongs to at least two people (sometimes not literally), it is theirs. Really, this extends to most everything you could think about. But, if you find yourself getting into the habit of using their as a neuter reference, stop. I'm serious. It is soooooo annoying. Use his, him, her, or hers. Really. Now onto my examples:
Their smelly, dirty dog infested the carpet with fleas.
Their loud hippie songs made my insides hurt.

God bless.