Is it necessary to smell the fluid to ascertain if it is semen, or is it sufficient to observe other characteristics of the fluid, especially if a person cannot diagnose semen by smell?

There is no requirement to smell the discharge to determine whether it is maniyy (seminal fluid) or not; it is sufficient to observe its characteristics for differentiation. The questioner is advised to avoid delving deeply and being overly meticulous in her inquiries, and to shun waswasa (whispers/obsessive thoughts), especially concerning maniyy and the fluids discharged by women.