What will your agent say when you hand them a headshot that doesn't look good? They will get annoyed and say you should have them done again. This is why it's so important to have a great headshot, especially if you have an agent.
I can't stress the importance of having a good actors headshot because it's just so important if you want to get more than just background roles. Remember: you don't look like a professional if you just went to Kmart and paid $30 to get a photo of you. There is a difference in quality that agents can easily see.
Everything about you shows through the quality of your headshot. If your headshot looks shoddy and unprofessional and you don't have a great look on your face, the casting director or agent will think you're not serious about acting and will toss your shot in the garbage.
It's so important to understand this! There is no way you'll make it without a professional headshot and skimping on it is the same as punching yourself in the face.
What will your agent say if you walk in with a crappy headshot? You don't want to know.