"Bad" is relative.
If temperatures are in spec then the fan speed (whatever RPM) is probably okay.
If temperatures go up and you discover that the fan speed is running slower than before then the RPM (i.e., "923") could be bad.
Although I am sure there are generally accepted ranges for the rpm value, "good/bad" mostly depends on your system and system history.
Temperature is more important. An inefficient high rpm fan could cool the same as a more efficient fan at lower rpm.....
Sam_missles and others can probably provide additional comments and insight based on their experience.