Some things look iffy but aren't always a problem. It depends.

• Oily beans. Dark roasts naturally get oily. If it's a French or Italian roast, that's normal. But if a light roast is oily, something's off.
• A roast date that's 3 weeks old. That's still decent, but you need to use it soon. For a weekend brewer, that's fine if you'll finish it in two weeks.
• Unroasted or 'green' beans. Unless you're a home roaster, skip these. They won't taste good without proper roasting.

So don't panic if you see oil or a date that's not yesterday. Use your judgment.