Yes, even if I feel inclined to help, I'll gently direct them to the forum, with the comment that if I'm not getting paid commercial rates, I'd prefer the question and my answer to be googlable and contribute to the community, + they get the benefits of free peer review and alternatives that may be a better fit to their needs than my choice of solution.
However zero posters don't get that response - they get one of the reasonably polite 'go forth and multiply' responses above, the first with a timescale long enough to discourage students if I don't want to burn any bridges, the second if I truly don't give a s--t about their problem.
If you want me to take a project to PM (other than just for swapping contact details to send hardware) you'd better have interacted with me in the original topic, be willing to pay, and have a dammed good reason why it cant be kept open source, and I'll ONLY take it on if it fits my availability and I'm confident I can do a good job without needing to educate myself on your dime.