Mother has underarm odor, but son doesn't. Will it be passed on to grandchildren?

Body odor is the dominant inheritance of X chromosome.

Whether the mother has a son or not means that the mother (chromosome XX) is a heterozygote carrying genes (one X carries, and the homozygote carries two X's).

X on my son's chromosome XY does not carry the body odor gene. As long as the son and wife don't have body odor, her offspring 100% don't.

But if his wife also has it, as long as it is not homozygous, the probability that the offspring will have body odor is only 50%. If she is homozygous, it is 100%.