I love to use self tanner on my face too- it just makes my skin look younger. I keep it on my hands and arms all year as well for younger looking hands. I have been doing this for years, along with consistent use of sunscreens and at 53, with fair skin, I do not have age spots. I do have lots of freckles that with age have become paler and even they are less noticeable with self tanners. What I do get is a deepening of color of a few of the freckles on my inner thighs that comes from where the self tanner is settling into the freckle  and as the tan fades they stand out where the self tanner sort of stuck in those little freckles. That doesn't occur anywhere else and I think it happens there because the skin is very soft and fattier and isn't really a big deal because at that point it's time to re-tan and I just scrub the spots with a loofah or rough cloth and it washes right off. Never have a problem with the tanner leaving spots on my face what with the thinner skin that daily face washing and creams I use doing a gentle daily exfoliating thing. I think age spots come from the sun and aging and not from tanners anyway. Seems to me that your self face tannig to avoid the suns tanning is the right thing to do to avoid age spots.