Picture this: a five-year-old male neutered domestic long hair comes in for an emergency for lethargy, anorexia, and weakness. When the technician triages and obtains a full history, the owners report he is known to eat things, but nothing has gone missing that they are aware of at this time. They deny any vomiting to the technician, and they have other cats, so they aren't sure of urinary or bowel habits being awry. You go in after performing your physical and reviewing findings, differentials, and attempt to clarify a few things. Of course, you ask about vomiting. They say, "Well, not in the past few days." You follow with, well, how long ago was it?
The two owners in the room debate a bit about when, but from the discussion, it sounds like vomiting in their multi-cat household is a norm, not a rarity. Here is a perfect opportunity for client education about the causes of vomiting and to inform them that it isn't normal for any cat to vomit regularly. This will help lead your recommendations moving forward. It is crucial we relay to people that regular "hairballs" or other "routine" vomiting is never normal.
One of my biggest pet peeves is when clients come to me, as an emergency clinician, with an emergency, and when asked about chronic conditions/problems, clients do not mention vomiting. When I ask about vomiting specifically, I often get "Oh, well, yeah, Fluffy vomits about every other day to weekly" or, well, "Lucky gets hairballs a few times a month." Usually followed by, "But that is normal." Of course, I could go on. Please, please stop telling owners it is normal for their cats to vomit.