I guess I'm the exception to the rule then. I studied software development in a prestigious university and worked as a developer for a few years and left because I simply didn't enjoy it and wasn't making as much money as I hoped. Admittedly I wasn't the greatest developer in the world but I was at the very least average. I left development to work in sales and eventually and (unintentionally) fell into recruitment. I currently work as an inhouse recruiter for a large development company and make significantly more money than what I could have expected had I stayed in development.
for a fairly-poorly compensated job.
Base salaries in agency recruitment are poor but if you do nothing more than hit your targets then you'll comfortably clear £60k a year in the UK whilst still in your early twenties. There are plenty of recruiters who would struggle to print 'hello world' in any language that still clear six figures a year.
Your advice about protecting your cell phone number is absolutely spot on though.
From what I gather, the UK and EU don't value software developers as much, so the bill rates are probably lower.
Don't let them near your cell phone number. Keep it off your profile. Put a Google Voice number in there instead. It's like Craigslist, there are advantages to using them, but you need to wear your big boy pants and take some simple steps to protect your privacy.
Recruiters are not technical and never will be. "I think I'll quit programming and start recruiting" -- No one, ever. Do not expect them to know anything about the jobs they're pitching. They're sales types, skilled at making connections with people, not machines. Try to appreciate that instead of demanding they learn two difficult skill-sets just for a fairly-poorly compensated job.
Keep each email to a single question until you've established that the opportunity is worth pursuing. Don't let them set the direction of the discussion until then. In the situation described, I would have simply asked, over and over again, "What is the salary range offered?" until they coughed up a number.
A recruiter found me my current job. I might be here a month until another recruiter will find me another making more money.