What are we trading?

I have a love hate relationship with doing trade work. I personally do trade work ONLY when there's an actual trade. The times I'll do trade work is if it's an idea me and a makeup artist has came up with and we need a face to bring that idea to life, or if I'm shooting someone who can expand my portfolio and actually help my career. In these cases trade work is fine because the model is going to get some great images and I get to bring a idea to life. I DONT do trade work when I'm only going to help your career. There's no trade in that. I get it, not everyone has money to spend on shoots or just doesn't take modeling serious, but this is my job! I don't mean to sound rude, but if I honestly cant use the images in my portfolio then why would I shoot it for free? Photography is more than a hobby for some of us and it's actually how we make money so when I get asked to do trade work with someone I really have to evaluate the subject and ask myself, is this something that's going to broaden my portfolio, or am I just doing someone a favor? Now if you don't take modeling serious and you really just want to shoot for fun I get that, but I don't necessarily shoot new subjects just for fun. For those of you who do take modeling seriously, why not just wait? Your better off just waiting so you can spend money with a photographer that's going to make your vision come to life, other than letting someone shoot it for free and get some terrible images in return.