I havent read this whole thread, but as a wife who does literally ALL of the laundry in my household, I thought it was worth my 2 cents….
Doing laundry sucks. Its a long, daily chore that nobody will do except me. So as unsexy as it sounds, when I go to do our laundry (my husband and I share a hamper), I’m in “work” mode and just trying to get it done as quickly and painlessly as possible. I’m just grabbing 2 armloads and carrying as much as I can to the laundry room. I’m never inspecting what’s on top and what might look out of place. I feel like the only way I’d really notice is if it was absurdly prominent or if it was fresh and I felt it.
As the husband who does the laundry in my house, I still don't think I'd do it in my wife's panties! I have jerked off into my boxers before, but separate story.