Trade, TF, collaboration, TFP, TFCD… whatever you want to call it, it’s basically professionals working together with no money changing hands; the only payment is the pictures.
The question is: why would anyone do it? And the only answer can be: because they want the pictures. If a photographer thinks a model would look right for some ideas they have, then it’s worth it; likewise, if a model likes a photographer’s work and thinks the pictures would look good in a portfolio – and generate more work – then it’s worth it.
But the golden rule for a model is: if you don’t like a photographer’s pictures then don’t shoot trade with them. Simple. There is just no point, even if you’re just starting out, to shoot trade with someone if you don’t want the pictures. It sounds obvious but a lot of people forget it.