Well, obviously tracing and copying are a legal matter, if the person is trying to sell them. I can't respect someone tracing a piece of art and trying to sell it for $100. It wasn't their own work and therefore should not even be up for sale at all. Tracing and Copying should be reserved for practice, with the exception of preservation and repair artists whose entire job is to trace and restore the art that was already there. But THAT is well beyond tracing something out of a book.

I've learned the hard way the copying a painting really IS a lot of work. The end product is right in front of you, but you have no idea how the artist got there. So you spend forever mixing paints and trying different techniques to accomplish the same thing. We spent about a month and a half on our Copy project in my painting class. And then he FORCED us to stop because we were all going out of our minds with OCD.

So, copying and tracing can be extremely beneficial, not just to beginners. It's something that can show you how another artist achieved a successful piece of work. And you can use whatever you learn and reapply that kind of knowledge to your own work. A lot of my art teachers, that are professionals in the field and hold galleries and such, keep a notebook of studies where they do exactly that: copy another person's work for study purposes.

As for references, I think it's BEST to try to find someone in real life that will pose for you, or at least go take your own photos. It will save you a lot of money and legalities. Otherwise, find someone with decent reference photos specifically posted for your reference and properly accredit them. Save the "go online and look up a cartoon picture to reference" for your private journals. I have one project that I used someone else's photo for, but I refuse to scan it and post it online until I contact the person about it and see what they say. If they say no, then it remains for my own personal files.

I can't agree that copying is disrespectful, though. In fact, it really is flattery. It means you found something about that image that connected with you and you felt so moved that you wanted to create something similar. It means you really like their style or whatever message they had to say. I DO encourage everyone to discover their own ways of doing things and their own art styles, but it is a form of a compliment to copy someone's work.