There is actually another example later in the series of being drunk allowing one to see Sam, at least partially. In Hurricane when Sam and Cissy attempt to evacuate the hurricane party the clearly drunk host with the mustache suddenly double take blinks at Sam and comments that his hair is changing colors:
"Brown hair, black hair, brown hair, black hair".
(As a side note, in the first scene of this episode Cissy actually gets a glimpse of a different eye color than she's familiar with or so is implied by her random comment that for a moment she'd thought his eyes looked green. Though she is not drunk so I have no idea how to explain that).
Wow I'd completely forgotten about the drunk partier from Hurricane, guess it does back up my comment that drunk people may be seeing something off about Sam...
In A Portrait for Troian There was also Ms. Stolz whom is revealed to be a ghost, she makes a suggestive comment. She informs "Tim Mintz" that he'd received a message from some woman, I can't recall exactly. If memory serves she makes some kind of implying comment that she can tell that his response to the message is off and then says:
"Strangers aren't welcome here." or something to that effect. True Tim Mintz was also a stranger to her but something about the way she said it, with warning in her voice tells me she'd directed the comment at Sam.
I also believe she locked Sam in the study while Jimmy was making his move with Troian intentionally.
Ahhh, Ms Stoltz. SO much to speculate about her. I watched this episode a couple of times myself in the past couple of days to write the episode recap and my segment for the podcast. We know perfectly well that dead and near-dead people can see Sam and Al, so she really must have been seeing Sam.
As for the message, Tim had asked for Mrs Little from the newspaper to do some research for him and bring him some newspaper clippings. Mrs Little was going to drop them off at the Claridge Manor, but advised Mrs Little to not do so and that Tim/Sam would pick them up the next day. Sam thinks that was wise due to the storm, to which she replies "It had nothing to do with the storm. Strangers are not welcome here!"
It is at this moment that Al appears, freaking him out, as she glared right at him during her "Strangers are not welcome here" line. It would make perfect sense that she would also be seeing Al and saying that comment to both of them - after all, both of them would appear to be strangers to her.
It's also quite possible that she didn't want Mrs Little to come to the manor, as Mrs Little knew all about the Claridge family history, and might be able to piece together who Ms Stoltz actually was - after all, once the bodies were discovered, it was Mrs Little who commented that it was odd that Troin's housekeeper would be named "Stoltz" when that was Priscilla Claridge's maiden name.
What I find strange is that she just goes about her business as though Sam is Tim. Then again, as a ghost, maybe all she cares about is her unfinished business. Which brings up another point, just WHAT was her unfinished business? There are a few possibilities, and it depends on whether you think Ms Stoltz is good, neutral or evil.
If she is evil, she might be like a poltergeist, simply making trouble because she can. Either that, or she is just angry at the world and wants people to suffer. This would explain why she locked Sam up in Julian's study - either she was trying to make his life more difficult or she wanted Troian dead.
If she is neutral, she might just simply want her body found so that she is not forgotten. I don't think this is likely though, she had too much influence over the household to be truly neutral, not to mention her locking Sam in the study would be completely out of character if this is the case...
If she is good, then she might be watching over the house and the current master or mistress. I think that this is the most likely explanation. Even though she is rude and melodramatic, Troian states that she is a good woman, and Ms Stoltz definitely shows a great deal of respect for Troian. I think she was perfectly aware that somebody was trying to drive Troian insane and eventually kill her, and actually wanted to protect her. Unfortunately, she thought that it was Tim/Sam who was the culprit. This means that when she locked Sam in the study, she was actually doing it to try to PROTECT Troian. It's just lucky that Sam was able to escape and save Troian from the real culprit.
Whatever you think about Ms Stoltz, she was bound to the Earthly plane by some unfinished business. Whether it was to cause havoc, to protect the house and its mistress, or just to ensure that her body was discovered, once Troian was safe and the body was discovered, she had no more business and so was able to pass on. Just what she passed on to is a mystery - although some people in the fandom like to believe that she went to Hell and was later recruited by the Devil to be a part of the Evil Project Quantum Leap, and took on the new name of Zoe. I personally don't believe this - despite her rudeness and melodrama, I think Ms Stoltz was a good person and so finally found peace.
The So Help Me God reference makes no sense to me although I admit I haven't watch that episode in ages. Sam does not look old nor do I recall Leonard being significantly younger than Sam.
Leonard and Houston went to school together, so they would both have only been in their twenties. When Sam comes to interview Myrtle, he speaks to Sadie for a moment and she comments about him looking older than she remembers. Then in the courtroom she says he looks haggard. Now it's quite possible that the stress of the case might be showing on Leonard's aura, but I doubt it. I just think Sadie was seeing something off about Leonard - her mind was near-alpha-state and so might have been seeing something off about him.
Though don't misunderstand, I do NOT deny that Sadie's mindset would indeed allow her to see Sam. My bestie and I have observed that her testimony in court had a creepy vibe to it similar to Laura Fuller of the Trilogy episodes.
Now I'd like to point out one more early example of Sam being even a fraction noticeable. In Genesis during the BBQ after Sam and Peg kiss in the back doorway, Peg touches her fingers to her lips accompanied by a startled expression which screams that she felt that her husband's kiss was different. Amazing catch by the way as I don't think that something most people would be able to pick up on.
Great catch! I never noticed that, I just assumed that Sam was kissing her differently than Tom had. But it's quite possible that the aura doesn't affect the touch of the leaper. In fact, I seem to recall an episode where someone commented on Sam's host's hands not feeling the same as they had remembered.