I disagree with Lee here. I don't think 'scantily clad' does carry a negative connotation. To me 'half naked' sounds a lot more negative. To be frank, I wonder if he was not taken aback so much by the wording, but by the mental image it gave him.

Gabriela's English is wrong, but she does have the right idea about the connotation of the phrase 'scantily clad'. It isn't weird, but it IS loaded with sexist assumptions. We generally use this phrase to refer to young, attractive women, together with the assumption that this style of dressing is alluring in some way (either intentionally or unintentionally provocative). It's the same as describing a garment as 'revealing' i.e. revealing their attractive bodies. We would not use 'scantily clad' for a man, or for an older and/or non-attractive woman. Would you say that your granddad went for a walk 'scantily clad'? I don't think so. To be honest, " some girls like to be scantily clad when they are alone at home cuz it feels very comfy " sounds like something from a soft porn chat line.

I prefer use: This girls was with few clothes... Because, "Scantily clad" means that a girl use this stile tipe for to provoke.

In most situations, "scantily clad" does seem to show the speaker's judgement of that person, so I'd say, yes, it is usually negative. To sound more neutral, you could simply describe the person's appearance plainly by saying that they are "wearing little clothing." Some people might say that a person "dresses comfortably" while at home, which sometimes means that they are wearing less than what they would in public or simply wearing pajamas or clothing like it. If a person is in their underwear, you might describe them as "half-naked." I think how you describe a person's appearance depends on the occasion and the intention of the person for wearing what they are wearing. If clothing is not suitable for a particular event, then you might say that they are "inappropriately dressed." If you want to describe a person's clothing positively despite it being revealing, you could describe it as "fashionable," "beautiful," "seductive" (if you want to draw attention to its revealing nature), etc.