I don't believe the coin toss is really 50-50 as we have always been led to believe by statistics. statistically the assumption is correct of course; stats being stats. In practical reality the engravings make the two sides, however infinitesimally, uneven.
This affects the spin because of effects such as; gravity, air resistance, magnetic characteristics of the metal of which the coin is made and the force of the toss.
Separately these factors won't affect outcome much; but in synergy with other factors not mentioned here to avoid rambling, the outcome will more likely  be 49.999... - 50 Heads to Tails each time. thus making the "odds" in say a million tosses slightly lopsided indeed!