I feel like people forget this command exists.
I think originally this would check if someone was currently poisoned or diseased, and that was all.
Since we have so many more addictive substances in the module now, how about expanding the tool to detect if someone is suffering from withdrawal or under the influence of drugs? Maybe based on heal + spot.
Then add an option to do a more thorough and invasive check that could be resisted unless subdued or unconscious to determine what the substance is, based on heal, lore and herbalism ranks.
Detection of supernatural or outsider influences should still be handled through RP.
Physician rogues could also get a bonus to the check.