What is the ruling on wearing clothes that have been touched by semen and prostatic fluid due to a wet dream, knowing that they have been washed, and a slight dry trace of them is found therein?

Semen is pure according to the preponderant opinion, but it is better to wash it to avoid disagreement. Pre-seminal fluid (madhy) is impure and must be washed by immersing its location in water. A dry trace after washing might be from semen, which is pure. As for pre-seminal fluid, no trace of it remains after washing. Therefore, the clothes have become pure, and prayer in them is permissible. It is permissible to benefit from an impure garment by wearing it outside of prayer.