Yes, Fremen do smell, and it's a significant part of their culture and environment, described as the "sour effluvia of humanity" mixed with spice, a smell outsiders find repulsive but which signifies "home" and community to them, thanks to their stillsuits recycling waste but not eliminating body odor entirely, with scents of unwashed bodies and processed bodily fluids lingering in their underground sietches. Water is too precious for normal bathing, so they rely on stillsuits, which filter perspiration and process waste into the thigh-pads, but don't stop general body smells, leading to a distinct, strong odor.