If you’ve not studied KonMari, it does seem a bit weird and fluffy at first, @Minioooons. But if you work through the process step by step properly, then you train yourself up to recognising very easily what sparks joy for you, and quickly your life doesn’t have to be burdened by clutter anymore.
If you do the stages properly, you start with preparation, where you envision the life you want to have, and the person you want to be. Once you’ve got a clear idea of what that is, then you can begin.
You do clothes first, then papers, then books, then miscellaneous items by room, then sentimental items. By doing it in this order, you can train yourself up to recognising the feeling of joy.
In your example, when you start with clothes, you start with the clothing items worn nearest to your skin/heart first, so pants, bras, socks, etc. It can be confusing to think, “Why would this pair of tights spark joy for me?” because nobody gets very excited about tights. However, the spark of joy comes from the way you feel when you wear them. If you have a nice pair of tights that you think make your legs look awesome, or a cosy pair that make you feel warm, then that is the spark of joy. If your tights are bobbled or overstretched, or are in a colour you wouldn’t want to wear, then they don’t spark joy, and they need to go. Thank them, and move on from them.
KonMari isn’t about chucking loads of stuff away. My DH and I are quite minimalistic nowadays, but my living room still has pictures and some ornaments and candles and loads of books, because they spark joy for me. KonMari just doesn’t hold with keeping stuff “just in case”, or because you will feel some sense of guilt of getting rid of it. If it doesn’t spark joy for you, then it’s a burden on your life.