Subtle clues for PCs with high perception

[RabidBadger31]

I'm running a two person campaign where the two players are these kind of detectives/investigators. One is a half orc fighter/ thief with a custom background of bounty hunter. He plays the badcop, finger breaker, type that has no qualms with beating a confession out of someone. The other is a half elf bard with a high charisma, intelligence, and wisdom. He has the charlatan background. He already plans on taking the observant feat at 4th level as well expertise in perception and investigation. This is going to give him insanely high passive checks something like 24 or 26. I have no problem with this. I think it's kinda cool that he's building a Sherlock Holmes type and it fits well into this campaign. I just can't try to hide secret doors or subtle things like that. What I'm thinking of doing instead is dropping absurdly tiny clues like a ring being on a different finger or the faint scent of lavender imminating from a candle. Things like this that only he notices. Some will be red herrings and others will be completely innocent, but some will be actual clues. I have some ideas for these tiny clues but I would love to hear more ideas.

[Person_Man]

You might want to read through some 1E modules, or more recently published "old school" games. In them, DMs elaborately described every room/NPC/etc, and players had to describe how they wanted to search the room, disarm traps, interact with PCs, etc. There were far fewer checks or abilities related to resolving such things, if any. (Google "A Quick Primer to Old School Gaming" for a more elaborate explanation). It lends itself to a lot of "detective" style campaigns a lot better then modern rpg, which tend to resolve such things mechanically. (So that you can get to combat or roleplaying more quickly).