What is the success rate for junk mail?

I got back recently from a month away. After unlocking the front door I was met with a lot of resistance as I pushed the door open. On the floor was a months worth of letters, bills, leaflets, charity bags and other assorted detritus. Fortunately, the era of free local newspapers is long gone - or the front door might not have opened at all. (Although I do get sporadic, small glossy "community" magazines - which just seem to be ego trips for their blogger-authors. People who have too much surplus time and money - and no, the irony of that statement is not lost on me).


After I'd unpacked, turned the water back on, flushed the pipes and made some tea I started sorting through this mountain of paper. Apart from about a half-dozen bills (some red!) and statements, there was nothing else that concerned me. However the pile of unwanted material numbered over 100 items and stood a foot high in the recycling bin.
Now I realise it's only us poor fools who use stamps, who pay anything close to the retail price for postage, but the sheer cost of sending all this waste paper to me would I guess, be somewhere around £10 - whether it was delivered by the postman (who probably now has had his/her industry redesignated as "advertising", since that's where the bulk of the work comes from), or by a hoodie'd lad with an iPod pushing bits of paper and plastic through people's letterboxes.
But do any of the organisations who send this stuff ever get any replies? Do they get enough people filling in their little forms, or calling their phone numbers to recoup the cost of printing and sending out their literature? If even one person in a thousand picks up a leaflet, glances at it on the way to the shredder and thinks "oooh, that looks useful" and then if even half of those don't immediately forget about it and follow up - can the sender make enough money from that one sale to cancel out the other 1999 who immediately tossed it or found something else to take their attention.


This is a different dynamic to SPAM emails - where, I am told, there is money to be made, as the cost of distribution is practically nothing. So even with a "hit rate" of worse than 1 in a million, the arithmetic of a very large discard rate combied with an incredibly low distribution cost results in a nice little profit, although being universally hated by everyone who knows you is another part of the equation.
Anyway, back to junk mail. Here the costs are considerably higher: material, printing and the manual labour of delivery. That should mean that the rewards are correspondingly greater, too. However I can't say that I've ever felt the urge to respond to a circular (as you will have read above, I don't even respond to bills sometimes) - even though, at 1 foor per month I must have received a pile nearly 400 feet high by now. Further, after asking people I know, I didn't get any positive responses from them - presuming they weren't too embarrassed to admit it.


Is this a case of the old advertising adage "Half the money we spend on advertising is wasted - but no-one can tell us which half". Or is there a certain segment of the population who readily responds to this stuff and therefore makes it all worthwhile (in which case, why not just send all this paper to them?). Or is the sad fact of the matter, that selling tat from junkmail still has such a high profit margin, that the numbers work out?
Still at least it all keeps posties in jobs.