To rephrase your thread title: I think the woman you mentioned are marketing to the wrong group when they practice these small deceits to misrepresent themselves.
I also think this issue is stemming from a flawed assumption created by the culture of online dating. IMHO, when you look at online profiles you are not "shopping" for your "perfect match," although many have been led to believe that is what they are doing. You can try and improve your chances of successful compatibility, but I think too much detail can work in the other direction and actually increase people's pickiness.
I think anyone who would label what these women are trying to hide as "deal breakers" would not be a good match for these women anyway. They are all trying to squeeze into molds built by assumptions and stereotypes. They are building on the flawed premise that there is something wrong with their arms, their accent, or their relationship history.
People are attracted to whatever they are attracted to, and we all have our biases. However, self-confidence and being secure in yourself is a universally desirable trait. If Emma likes her arms and wears short sleeves, great. If she likes her arms and wears long sleeves, also great. If she dislikes her arms, it is more likely the lack of self-confidence that will turn potential suitors off.
I don't think she is obligated to wear anything she wouldn't normally wear. A huge amount of women wear bras for lift - is a potential mate going to cry false advertising the first time he takes it off and we sag? If he does, he is a jerk.
All the girls mentioned need to be with someone who likes them for themselves.
We all "lie" a little when it comes to appearance, especially women. Most of fashion is meant to trick the eye. We accent, we misdirect, we tone down and highlight. We pad, cinch, cover, lift, straighten, lengthen, curl, bind, twist and color all kinds of body parts.
Men color the grey in their hair and beards, post pictures of themselves in a suit when they almost never wear them, and otherwise play up or down whatever they think will make them stand out and give them a better chance.
It is all marketing and it is all deceitful to some degree or another.
Open, honest and straightforward are better as a rule. I think if other people know about something than it isn't right to hide it from a date - they will find out sooner or later anyway right? If you fail to mention something and it comes up later, they will wonder why you didn't bring it up before. Something like heritage and relationship history are important, and I can't see anything gained by hiding or misrepresenting either. The relationship issue isn't a need-to-know thing, especially since it isn't indicative of what any future relationships will be like.
I don't think misrepresenting yourself is the real issue - but why you are doing it and what the ultimate result will be is an important question to consider.