If you urinate your normal amount and frequency, the body is well-hydrated, provided you don't have kidney disease. I think that's a better gauge than how thirsty you feel. And what a person drinks may make a difference. In the long run, whether drinking a sports drink or just water the primary issue still is hydration. In general, it's better to drink plain water than any other fluid, like a sports drink.
Sweat contains far more water than electrolytes, which many sports drinks contain.
But if you loose a lot of sweat for hours then you'll need to replace the electrolyte solutions as well. I get a rash every time I try a new shampoo. A new contact allergies testing clinic at the UA Section of Dermatology now offers patch testing for 60 of these kinds of allergens. People in certain occupations tend to be more susceptible to contact allergies. Hair dressers, mechanics, construction workers and people working in photo labs are among those who experience a greater number of contact allergies.