Is what was found of yellow spots on the garment after a dream involving seeing a man considered semen necessitating ghusl, especially with no sensation of pleasure during the dream and its smell being like normal discharge?

Love-sickness is one of the greatest impediments to reaching Allah. To understand the description of a woman's maniyy (seminal fluid), you can refer to Fatwas no. 102977 and 105294. If you doubt whether the discharge is maniyy or not, then choose and assign it the ruling of one of them, according to Fatwa no. 118035. However, if you see maniyy upon waking with its known characteristics, then ghusl (ritual bath) is obligatory, even if you do not recall having a wet dream.