Depends on the length of the key vs the message, but if the pad is 100 percent and has something approaching a random distribution, and the message length is suitably padded, and the results roll over in a modulo that is close to the information distribution, then all valid results become close to equally probable, so, while you may decode a message, it is very unlikely to be the message that was sent.

Still lots of ways to crack a poorly executed OTP.