Why are my cucumbers bitter?
Some types of cucumbers are more bitter than others, and that has to do with the variety as well as weather patterns. The stem end, skin, and layer just beneath it have the highest amount of bitter compounds, which is why peeling and discarding the end helps reduce bitterness.
Salt also helps, as it reduces our ability to taste bitterness, as does sugar (like using yogurt in a tzatziki sauce). On top of that, some people taste bitterness more than others, which is why two people can easily disagree when tasting the same cucumber.