I really just watch anime at random. I give it 3 episodes to engage me, if it fails at that point I find another.
Hunter x Hunter didn't have me after 3 episodes, but it's one of the few I stuck with and didn't regret. Still one of my all-time favorites.
It's mostly because of this that I believe the Harem genre to be one of the two genres that would be bad starting points for a newcomer.
I would recommend against starting there (unless it's your specific taste concept) because Harem is easily one of the most recycled and least innovative genres in anime. Anime is growing here in part IMO because there's really not a whole lot of other equivalents to it, particularly in cartoons but even in general. You see a lot of concepts ranging from flat out bizarre to intense to just plain interesting/mind**** type deals. Harem bypasses all that, occasionally throwing in magic dudes/girls/whatever but largely sticking to a formula such that you can predict the result by episode 1-2, even if you've only seen a few of them.
The odd exception that deconstructs that is way too much of an exception. At this point I think the writers need to just pick the "winning girl" at random just to troll people, even with the uneven character development and perhaps in spite of it, because even THAT would be an improvement on the formula ^_^. I did like the one where the dude had a choice of all kinds of different girls including several supernatural ones, his childhood friend, etc and picked someone else completely causing some bat **** crazy reactions in the process. There's another one where the dude sleeps around too much and gets murdered hahaha. I'll not name these as it'd be too spoilerish, but just because they were different, I liked them more than I might have on story/own merits.
Mecha has similar problems, though not QUITE as bad.
Inuyasha, generally considered a good starter since it has a lot of themes that are cross cultural while also being pretty simple, has the character Kagome. She is heavily sexualized throughout, naked bathing, people peeping, being captured naked, people trying to **** her, and a lot of the artwork is designed to entice you. She's 15 years old.
IIRC the age of consent in Japan is lower than in the US. But more importantly, when you yourself are in the 13-17 age range, it doesn't seem all that gross to think along those lines for someone who's 15 (in fact it would be common for younger guys). Combining the age of consent with the probable initial target audience of the show (likely teenagers and younger predominantly, it IS shounen right?) it's really not implausible.
I don't know, it affects different people differently. The fact that none of these people are real or even act very much like any real people I've encountered (aside from the occasional plausible decisions) seems to separate it from reality quite firmly in my mind, though I could see how it would bother someone if it doesn't.