Here's what I mean: Sally was tired and hungry and angry.
The writer does this all throughout the manuscript, almost every time they are listing words. As a reader and writer it starts to irk me and I believe writers should try to stick commas in between unless he/she is trying to emphasize the words, by repeating "and". Though emphasis is lost if one constantly and repeatedly uses "and" multiple times in a sentence. Just my two cents.
Remember grammar is important. The writer who says they don't need to know how to spell or use grammar correctly and believes that their agent or editor will handle it, is the one who ends up with an unpublishable manuscript, which no one will want to spend time cleaning up.
So remember edit, edit, edit, and then edit again. Then it'll probably be ready for an agent.