I don’t know about you, but I’ve dealt with some bad clients before and it’s hard to really like doing design for them when they control the whole project. It turns into a battle of them controlling what you design, even if it’s not good design or what’s best for them. I think if the client is a really good source of income or they are a good client to have as far as networking, then I would keep the relationship. If there’s more stress and headache than what it’s worth, I would stop working for them. As designers, it’s our job to create what people want, but not sacrifice our wellbeing over it.
Don’t let people take advantage of you, and definitely don’t let them try to get more work out of you without paying you. Something they don’t realize is that we have to make a living too, and that graphic design isn’t just drawing pretty pictures. You need to educate clients on what you do, can offer, how much you charge, and have estimates for them to sign so that they don’t end up not paying you. That way, if they refuse to pay you, you can go to small claims court and show that they willingly signed up to pay you and knew what they were getting into.
I know this isn’t a pleasant thing to talk about, but saving yourself from being used is better than finding out the hard way; I know I had to.