I think I want an iguana, but my mom dislikes the idea...?

Well, I like iguanas and I really want one. However, my mom thinks it's a bad idea.

I think she was influenced by the fact my brother owned one a few years ago, and it wasn't cared for properly. Plus, she's afraid of lizards, lol.

His iguana often had little red bugs on it. Plus, it was kind of sick because it wouldn't eat.

What are some reasons that could have caused the bugs and the issues with eating?
I want to convince her that I can care for one better than my brother.
How can I convince her?