If you had an extreme physical eyesore that wasn't visible while wearing tshirt and jeans, but you know its a major turnoff how would you approach this when you start dating someone new (that hasnt seen this "side" of you)

Definitely not on the first date, it really isn’t their business until you’re both at a point where a physical relationship is going to happen. Honestly, I wouldn’t worry about it, if they like you, they’ll get over it. Most decent people don’t care when it comes down to it.

And I think people would notice a prosthetic limb far sooner than that point.

don’t release that type of info on a first date. just take the first date easy and see how you two click. They at a later date release the info. unless for example say you have a prostetic leg and you walk with a limp or what appears kind of odd. if the question would be brought up about how you walk then answer why you have trouble getting around. or with the example of a scar. would it be noticable with the type of clothing you would wear? if so then they may inquire about the scar. if a question was posed, It would be best to answer as honestly as possible. As asmonet said, ‘if they like you , they’ll get over it”

softly softly catch your monkey :-)

I agree it isn’t something that needs to be brought up on a first date. In fact, it wouldn’t need to be brought up until you were getting close to the point where your date might have a chance of seeing it. Honestly, I think that if the person is right for you, it won’t be a major issue. Everyone’s idea of what’s attractive and what isn’t varies. One person might turn tail and run, and there’s not much you can do about it; yet another person won’t even bat an eye.

Stretch marks are a bummer. (don’t know if that’s your hidden flaw but it sure was mine, until the tummy tuck anyway.)
Express your concern just before you are in a position that they will see it. Tell them you’re self conscious and I’ll bet you get all sorts of reassurance about how attractive you are.

All these answers are good, and I especially resonated with Judi’s answer.

My take: where are you asking the question from?

Are you feeling nervous or ashamed about it?
What do you really want in a relationship, anyway?
Do you want to be loved and accepted for who you are?
Are you willing to be vulnerable and intimate?
Are you willing to trust someone?

What’s the best way for you to take care of you?

I would bring it up, but not show, if it is the result of something beyond your control. A friend is in a relationship with someone who, several years ago, accidentally bumped into a lit candle on Halloween night, and set himself on fire. He has burns on his front and back torso, and spent months in the hospital. The experience had influence on who he is today, so it was important that it be told.

Everyone has defects. The external ones are easier to deal with than the internal ones.

It would be the first thing I would show. If the person is still interested than I have found a winner.

I do, and I don’t bring it up until it looks like there might be a reason for them to know. It’s for the exact opposite of the reason Gambit states, though.

If I show someone the Horrible Thing, they will probably run away, and it’s true that if you have someone who doesn’t, they’re a winner. On the other hand, most people judge by looks at the beginning of a relationship, so there’s a great chance that the Horrible Thing will be the biggest deal-breaker. On the other hand, if they get to know you and like you, there’s less of a chance that the Horrible Thing will make them run away because it’s not the biggest thing they know about you. They know your wonderful personality, sparkling intelligence, and great cooking, and oh yeah, there’s a Horrible Thing that is outweighed by these. They never know all that if the first thing they learn is that you have a Horrible Thing.

If and when it comes time to tell about the Horrible Thing, I just explain what it is, why it exists, and don’t be too shocked if I don’t look like all the other women. It’s usually shocking at first, because they’ve never seen something like that before and they’re not used to it, but a little knowledge about the Horrible Thing and about you being a wonderful person who has a Horrible Thing (and not just a Horrible Thing with a person attached) can go a long way.