I use topical magnesium every day and haven't noticed any taste.
I think it's wise to eat mineral-rich foods, especially foods rich in potassium and copper, when supplementing with magnesium and zinc. Potassium and magnesium need to be in balance, as do zinc and copper. We need very, very little copper, though, so no need to eat a lot of copper-rich foods, just keep them in mind. We actually need an awful lot of potassium and magnesium. It takes about 7 bananas a day to provide the potassium that an active or stressed person needs.