For starters, I'm bald.
Re: ants -- yes the ants do affect the taste of the nectar. All ants have the same venom as bees and wasps and are classified as hymenopterous insects. While drowning in the nectar they are likely secreting venom and pheromones. The venom would add a very acidic bitter taste to the nectar. As for the black ants, they are likely Campanotus sp. or carpenter ants. Believe it or not, you can get a whole degree in ants...and I got one ! lol
To stop the ants, I put my feeder on a shepherds hook and plaster vaseline all over it. Every couple of weeks I top it up.