Oh I agree with every word of this. As I mentioned, when I first watched the episode I wanted Buffy to give the guy a chance at first - I'm older now, and have more sympathy for my mom, more forgiveness of the past, and so I wanted Joyce to have some happiness on her behalf. (Just like I want Buffy to be happy on behalf of myself.) I mean, he cooks! (My second stepfather was a great cook though; that should have tipped me off right there. Not kidding.) He's generous, and unstuffy and he makes Joyce happy, and he's John Ritter! I grew up watching him on the comedy show "Three's Company", and he projects "likability". Comedy hijinks will ensue, right? And THEN...

And it always scares me that sequence

Exactly.

And I think a lot of people - on the show itself and in fandom - chalk up Buffy's intuition to Slayer sense, or at least that's implied - but I don't think that's the whole story. Kids are remarkably attuned to what's going on around them; and in households where there is abuse, you have to be. It's about survival. Buffy's parents are divorced, she's grown up listening to them fighting, she's had to develop a very sensitive antenna. I think her Slayer skills simply interlock with or enhance what she already possesses. She's a good Slayer because of who she is, not the other way around IMO.