This has NEVER happened to me before, but....
My sim had accepted the adventure to go into the secret hideaway of the Morcucorp base, which is under the Lufti house. (the James Vaughan adventure) Since it happened to be the middle of the night, my sim snuck into the house and was easily able to get to the secret stairway to go down to the secret base. The two Lufti sisters who lived there, were sleeping upstairs and not in the master bedroom downstairs, which is where the secret staircase is.
So my sim went down there and had the combination to unlock the first floor since it was on the toilet paper. LOL But once she got to the second floor, and was trying to follow the lights, she was having trouble getting the correct combination. So while she's down there stepping on all the floor switches, the woman who lives in the house came tearing down the stairs in her nightgown and ran into the room where my sim was and started yelling at her!! I'm assuming she told her to leave in Sim language because the next thing I know, my sim gets the base camp icon come up and she's about to leave to go back to base camp!
I was like, "Uh no you don't! You only have one more day on your vacation to increase your visa level...you're staying!" So I teleported her over the wall and past the locked doors so she could go ahead and go down to the next level. LOL I was laughing my butt off the whole time! I never had any of my sims get busted from going to one of the private homes to do an adventure.
Anyway, my sim completed the adventure, but I think she was pretty shaken up. She's got the "good" trait, so I'm sure it bothered her to be caught breaking into someone's basement.