good question there really isn't anything bad for it there are products that I feel are better than others.
I believe Armour All is the only product long term that can dry rot your tires.
(this will be over time)
the key for good looking tires I believe is after every few washes you should clean the tires with a good apc or something like Stoner's Tarminator wipe all that dirt and grime off the tires for a good clean base, then apply the tire dressing to it.
another tip after you finish dressing all 4 tires go back to it and wipe off the excess, this will ensure no tire slinging.
Adam's Super VRT is our shop favorite for a nice dark sheen