Praying separate from the main rows due to odour, and masjid etiquette

Answer

*Wa alikumus salaam.* It's disliked (makruh) to go to the masjid with any strong, offensive odour that might disturb others, out of respect for worshippers. If the smell is mild and unlikely to be noticeable, it is not much of a concern. It's best to remove or minimize any smell before going — consider a change of clothes or using fragrance (i'tir).

If, however, a person prays at the back, separate from the immediate rows, their prayer remains valid as long as they can clearly follow the Imam's movements, and they still receive the general blessings of praying in jama'ah.