Mostly for con rod but really shot crank bearing could introduce rotational slop -- but will also allow the crank to wobble a bit.
Bottom line here with this check -
- if you feel sloppyness then you have a problem. You need to tear it down. End of story.
- if you don't feel slopppyness then you still *might* have a problem. If there is other evidence then pull the jug. Otherwise, go ride.
Do you mean, crank bearings or conrod bearing?
The only way to correctly determine wear is to check the specs and measure with correct instruments as per manual.