Most of us tend to think red=right, though there's no guarantee that every manufacturer implements it that way. About the only time this would really matter is if you were comparing LP and CD of the same recording, in which case you would notice that the stereo image had flipped.
Also, occasionally you get a record where the liner notes say, "Guitarist A is on the left, Guitarist B is on the right." You might go through life thinking Beck is Page and vice versa. If you really feel the need to know for sure, you can: 1) RTFM; 2) ask the manufacturer; or 3) get a test record that has some clearly labeled single-channel tracks.
Also, occasionally you get a record where the liner notes say, "Guitarist A is on the left, Guitarist B is on the right." You might go through life thinking Beck is Page and vice versa. If you really feel the need to know for sure, you can: 1) RTFM; 2) ask the manufacturer; or 3) get a test record that has some clearly labeled single-channel tracks.