The recessive genes located on X-chromosomes in humans are always-

Human males have one X and one Y chromosome (XY). Most genes on the X chromosome have no corresponding allele on the Y chromosome.
So a male has only one copy of each X-linked gene; he is hemizygous. A recessive allele on his X chromosome has no dominant allele to mask it, and it is always expressed.
Females (XX) express an X-linked recessive trait only if they are homozygous recessive; heterozygous females are carriers.
Examples: colour blindness and haemophilia are much more common in males.
Such genes are not necessarily lethal or sub-lethal.
So recessive genes on the X chromosome are always expressed in males.