I agree with Karin and Ariadne. This is a question that cannot be answered or analyzed in one or two paragraphs.
Most of my clients are not interested in how they look but mostly how fitness can help them survive in their daily routines. My clients are mostly military and law enforcement personnel, so this makes my job easy ;-). But, I also have clients who even though they did start training with me with the expectations of looking better, they very quickly realized of their abilities and capabilities as humans and slowly they turned focus into how far their body can go. Their goals changed over the course of their training and they shifted their attention form looking good into what they can achieve if they really try. There is nothing wrong with taking in clients who just want to look good. Everyone is different and they have their own reasons as to why they want to get involved with fitness (and/or hire a trainer).
We live in a society where false advertisement and expectations are ruling the market and unfortunately we also have to be part of that world. The only thing I can control (and that’s not always the case) is how I can connect with my clients and to stay true to my philosophy and beliefs. No matter what we say here and/or try to change the world, that won’t happen. Unfortunately most people are driven by money and we are not different. If someone comes to me and says I want to look good, I will not turn him/her down. But instead I’ll do my best to deliver what the clients wants and then use that opportunity to pass along my philosophy about fitness and how I can help them achieve goals more important than just “looking good” (if they are open to it).
Each one of us comes from a different background and experiences that transform our philosophies. These factors come into play when we put ourselves out there and the types of clients we are seeking to train (no matter what kind of advertising and marketing is out there).