Do clothes become ritually impure and prevent prayer if one falls on dry street asphalt or asphalt wet with water? And do clothes become ritually impure by falling on street pavements? And is the clear liquid that exits a person after intercourse ritually impure?

The default state for things and places is purity, unless their impurity is proven. The evidence for this is the Prophet's (peace and blessings be upon him) saying: "The earth has been made for me a place of prayer and a means of purification."

Therefore, one must abandon obsessions and doubts, unless the presence of a tangible impurity on the ground or street is certain. In this case: - If the impurity on the ground is dry, such that nothing adheres to a dry garment, then the garment does not become impure by touching it. - If the impurity is wet, or if the garment is wet, then whatever part of the garment has been affected by it must be washed when purity is desired.

As for the fluid that exits hours after intercourse, if it is maniyy (seminal fluid), it is pure according to the soundest opinion. If it is madhiy (prostatic/pre-seminal fluid), it is impure.