I don't "snoop" as in searching, opening closets or cabinets without good reason (good reason = the roll of toilet paper is empty and I want to find another one).
Sometimes, however, people have closets with shelves but no doors, and leave stuff lying there... or they leave stuff on the counter near the sink or on the bathtub. I've seen intimate hygiene products, Vaseline, oral contraceptives, laxatives, suppositories, thermometers... I don't recall anything as obvious as a thermometer over a Vaseline jar though. Also, in France Vaseline is more commonly sold in tubes than jars, so no opportunity for seeing "tracks".
At some point I was sick at home. My wife left the thermometer, Vaseline (or was it jelly?), cotton and alcohol on the bedside table. I was visited by a colleague (I had left a dinner with colleagues due to stomach pains the evening before, the colleague was worried). I was very uncomfortable but tried acting naturally. To this day I still wonder whether the colleague did not notice, or just acted politely by not taking note.
By the way, I think that the "right thing" to do if seeing enema / douche / thermometer / intimate hygiene products / contraceptives / suppositories / sex toys by accident in other people's home is to act as though nothing happened.