With all due respect, we are sexual creatures. In my opinion, all women are sexy in their own way, regardless of how she dresses. I certainly think my husband is very sexy and I am very sexually attracted to him, and vice versa, and there is absolutely nothing wrong with that. (Don’t you think your wife is sexy??)
I’d certainly only marry someone I were sexually attracted to and then only someone who were also attracted to me sexually. On the other hand, I wouldn’t exactly like to be referred to as a “sexy beast” or anything of the sort. And I’d rather be referred to as handsome or dashing than sexy, to be honest.
My point is basically that sexuality, at least taken to that point, is something we live out between the husband and wife, we don’t need anybody else to desire us sexually, and certainly not multiple people. This is related to monogamy.
Sexuality becomes wrong when it is exploited and used in the wrong way, but it is not wrong in and of itself. It is actually very good, and is part of who we are as human beings.
Again, as far as sexual desire goes, it should only be awakened consciously between husband and wife, perhaps with the allowance that there’s nothing wrong attracting people to marry us, in which attractiveness plays some role. But we really don’t need to be widely desired or desired by everybody we meet or anything of the sort. And we definitely shouldn’t want to desired inordinately, i.e. lusted for (as in Mt 5:28, i.e. committing adultery with us in their hearts).
As I said, it all depends on how it is worn and the nature/intention of it. Where I come from, 2 piece bathing suits are perfectly normal and acceptable. (a lady would get much more stares and attention if she showed up wearing one of those muslim swim suits) The modesty line at my beach doesn’t usually get crossed unless someone shows up topless (if female) or wearing a thong.
No specific examples please!

It’s not about inches or centimetres. It’s about the intent to provoke lustful thoughts or, within limits, acting despite the knowledge that this is taking place (e.g. an attractive person can’t really say he or she doesn’t have need of clothing any more because the sun is great and he or she doesn’t care about any temptation others might be having… even then, such a person could actually pose less temptation than people wearing some of the things modern designers design).
The problem here is chastity, modesty etc. That we confine our sexuality to living it out with one chosen person (of the opposite sex, naturally) for as long as we both live. That we don’t attempt to command or control people using our sexuality (this includes proving to them that they can’t resist desiring us). That we don’t engage in imagining sex in our mind, that we don’t attempt to have others imagine having sex with us (Mt 5:28 issue), that we don’t awaken in people desires they have no means of fulfilling. That we don’t say “it’s not my problem” when we run a real, serious (not just remote or imagined) risk of leading a fellow human being into temptation (this isn’t a male vs female issue or a war for power between the sexes, it includes also a person suffering from same sex attraction, who may be forced to use the same locker room). The exact size or shape or other parameters of clothing are a secondary issue and differ from culture to culture to a large extent. What doesn’t change is the underlying modesty and chastity.