This subject has interested me for a long time and when I read sometimes the tag lines get into the story and ruin my reading flow.
How a writer chooses to identify who is speaking can be problematic. In the heat of writing an exchange between two people some problems can occur. I know I've found this in my writing. The rapid exchange goes down with no bother to say who is speaking. Then going back and trying to discover who says what can suddenly seem not so bright. If the writer can't figure who is speaking, think of the reader. I've seen this in contest entries and even in published books and have to go back and try to decipher who is saying what. Sometimes I find speaker A has said something two times in a row. Calls for revision.
Another problem in writing a scene heavy with dialogue is the creative use of tags. The simple said, asked, answered are avoided for fancy words. Shouted, yelled. Suddenly a pattern evolves and the reader begins to wonder what tag the writer will use next. I've read books like this and I suddenly become more interested in seeing what the next tag will be. Not great for enjoying the story and maybe an excuse for the reader to put the story aside never to be seen again.
What about those lovely adverby. "She said quickly. He replied angrily. She asked softly. Here another pattern can arrive and the reader enters into the adverb alert. Another reason not to read on.
But just using said, though generally invisible to the reader can also become boring. There are ways to avoid this usage. Try a little action, using the speaker doing something. Mark's eyebrown arched. "What are you doing? "I don't care." A gruffness entered Ray's voice. Doing this becomes very important when writing scenes with a mutitude of cnaracters, making it easy for the reader to know who is saying what.
Making things easy for the reader to want to continue to be involved with the story is what it's about. Falling into patterns that turn the reader's attention to seeing what clever tag the writer will use, or having the conversation look like "follow the bouncing ball" can lose readers. So, whatch your tag lines and during the revision stage check to see what patterns if any you have put into your story.