A girl cuts her hair short, and soon after, gets attention from men. She concludes that she gets attention from men because of her short hair, when the reality is that she gets attention from men in spite of her short hair. Her shorter hair is not causing her to get more attention; it just isn't unattractive enough to turn off the men that still approached her.
Another example: a girl gets a new dress and wears it out, and gets attention from a man. She thinks "This new dress really works," concluding that he gave her attention because of her new dress, when really she was just cute enough for him to hit on even though he wasn't a huge fan of her dress - that is, he hit on her in spite of the dress.
I think one of the reasons the confusion occurs is that we (men and women) are always eager to have found one thing or another that makes a significant difference in our attractiveness, and this wishful thinking helps us ignore the distinction I've just described. However, this is not the only reason we ignore it. Men make the mistake often when they evaluate women. If I point out a girl and say "That girl's hair looks bad," one of my male friends will often respond with something like "What? No way man, I think she's hot." But when I point out that she is hot only in spite of her short hair, not because of it, the guy making the comment will usually take a second look, reflect and then agree with me. So even when our own ego is not involved, we (as humans) still make this mistake. I think the most important reason for its occurrence is that there are so many factors contributing to attractiveness that they cannot all be easily considered in isolation.
- When you are experienced enough with fashion, make your own decisions about what makes you more or less attractive.
- Get your male friends' opinions, but make sure you call their attention to the specific change (Try "How does this shirt look on me? Would it look better if it were tighter?" not just "How do I look?"). Make sure it is a male friend that does not like you, because most men that like you will tell you what they think you want to hear.
- When it comes to clothes, remember that almost every store has a return policy. Buy it, try it on a few times, and return it later if your (male) friends don' like it.
- Do not solicit or consider opinions from your female friends, your relatives or your gay friends. All of these are strongly colored either by their inability to view you in a sexual light, or their desire to avoid offending you.
- Ignore your hair dresser's opinion or (for clothes) the salesperson's opinion. Both have too strong an interest in your acceptance of their suggestions. It does not matter how friendly they are. In fact, you would be wise to trust them less when they are friendly.
Be especially careful of the distinction between "because of" and "in spite of" when you receive attention from men you have not met before, because they have no point of reference for your attractiveness (i.e. when you wore a better dress or had longer hair).
I am not suggesting that you reject the attention you get in these cases; I am merely warning you against jumping to the conclusion that new-found attention occurs because of a change you made recently, when in fact it only happens in spite of that change.