How would one know if the person they are dating is not lying through their teeth about essentially everything? There would maybe be some inconsistency that would be a tip off, but if the liar were good, there could be no sign.
I guess it depends on the person doing the reading and, as you said, how good the liar is. My perception of myself is that I'm really good at triangulating data and not just noticing inconsistencies but also gaps in presentation (I myself when younger used to be a decent "liar by omission" just to keep people out of my business); and so far in life I think I've done a decent job in my perceptions in situations where I've been able to confirm.
I was also burned a few times as a child and was dealing with an addict father, and I was also in a difficult marriage for a number of years, so I was very well-acquainted with the types of lies that people tell themselves and others. I've even had a few roommates who ended up being really whack (one was clinically borderline), so it teaches you a lot about how people can appear normal at a distance and then end up being more disturbed. It's all a learning experience.
But people used to taking others for granted, not having experience with liars, or not having a great big-picture sense of the truth map with another individual could find themselves in trouble.
The picture that I would present of myself online most certainly doesn't match reality. Not because I'm misrepresenting anything intentionally, but because it's impossible for me to convey all aspects of myself and those which are presented are selected. I could be a completely different person than my online significant other might think.
I think how people say things (and what they do / do not say) actually can give away a lot of information. The actual details offered themselves are just one source of information.
But typically you're looking for an honesty level and what people share vs not share, what gaps they leave in the information, what they gloss over, what they focus on, etc.
I mean, realistically, one also does have to assume that no one is fully exposing themselves to a virtual stranger. It would be inappropriate to trust someone who you haven't yet gotten a feeling for how much they'll respect you. I always go into this stuff assuming there are things I am not being told, and it's more a matter of whether that is reasonable discretion, stuff that has been overlooked, or a purposeful attempt to deceive either out of insecurity or for malevolent purposes.
It isn't possible to go swimming or to go out to dinner. There would be no walks outside in the middle of the night when it's too humid to stay indoors, for example. A physical presence is probably important for developing a meaningful relationship.
I don't understand how a person can commit themselves to another without being able to see what they are like in person, get an intuitive feel for them, and spend time with a physical them. With Skype, I could probably come to perceive someone I met online was my significant other and treat a relationship as a typical long distance thing. But the risks... getting played would hurt.
I tend to fall in love with the person first and the physicality comes later. I have some friends who I've never met in the body who I feel very attached to and suspect that if we were close in physical proximity, we'd spend a lot of time together / be very close.
I think for a romantic relationship where touch is eventually expected, as well as living together, etc., the physical element is more important. The relationship itself is one thing; but there are also many practical issues regarding personal habits, levels of cleanliness, loudness/socializing, etc. Life is not lived in the head. I have had a least one friendship that fell apart when we roomed together for a year or two because the physical aspects of being in proximity caused conflict / led to issues.
Impatience. I can be easily fed up with people and would certainly not enjoy sifting through potential 'matches'. Something about that is utterly unappealing. It would probably drive me crazy!! It would be weird to be one of... 10 girls being fielded simultaneously.
As one example of that, I've looked at "speed dating," and I just hate the entire idea from the get-go.
For me, I still tend to do best when I'm doing stuff I enjoy with other people and I end up being attracted to someone I'm participating in the activity with.