Is it obligatory to change or wash bedspreads and blankets every time if seminal fluid or semen from a wet dream reaches the clothes without leaving a trace on the bed, and does the bed remain pure in this case?

What is discharged during a wet dream is semen (mani), which is considered pure (tahir) according to the preponderant opinion (rajih). However, it necessitates a ritual bath (ghusl). There is no obligation to wash clothes or bedding that have been affected by it. As for pre-seminal fluid (madhy), it is impure (najis) and necessitates ablution (wudu'). It is obligatory to wash any part of the body that it touches and to sprinkle water on clothes (nadh) if they are affected by it. If one is uncertain whether the discharge is semen or pre-seminal fluid, they may choose to consider it either. If one is uncertain whether pre-seminal fluid has reached a particular spot, the original ruling is that it has not, and there is no obligation to purify it unless one is certain of its impurity.