True in principle, but its knowing what to play, and when to play it, which my mate does most of the time.
If you always look for a particular machine to play, then it isn't that hard (so im told) to tell if its dead or not, my mate said that with something like a, lets say £25 jackpot machine with repeat chance on the JP, you can usually tell after 2 or 3 quid weather its gonna pay soon or not by the way it plays.
There are some very subtle things that the machine will do to let you know its going to pay very soon as well, the key is spotting them. Some machines, the machine name at the top will flash a couple of times, or turn red, but without making any noise. Some machines, a button will flash down at the bottom by the reels, sometimes it will be the cancel button, on alot of barcrest ones the barcrest button will flash twice very quickly and the chances are you won't notice if you are on the board, or doing hi-lo gambles further up the machine, as you wont be looking at the reels.
Some machines will keep giving you small wins that just roll in, and getting you on the board or bigger features and killing you, which is normally enough to put off the average player, who may have put in £10, collected £15 or so off smaller wins and features, got bored of getting killed on the board and be happy with that.
A machine will only pay when it wants to, and deliberately ignoring things like, getting the amount of nudges you need to spin in a small win and deliberately not nudging it in, ignoring features, gambling small wins away for a while and deliberately losing like that can sometimes make a machine more likely to pay, because it wanted to pay all those smaller wins out earlier that were ignored, and because the machine is set to pay 78% it will sometimes go nuts and give jackpot, but even that is worth ignoring sometimes as mega streak is sometimes worth more than the JP itself.
Plus there are the old tricks that most people know for smaller wins, the three holds rule for example.
You have lets say a '7' on reel 1, something else on reel 2, and another '7' on reel 3.
If it gives you the hold option, you hold the 2 sevens, if it holds again then hold them again.
Most people wouldn't bother holding them again on the 3rd time, as they will think its never gonna come in this time because it didnt twice before, but if you do hold them again it WILL roll in another seven for a win.
This can often be had for £1 or so on most machines.
Observing someone playing is invaluable as well. See what they put in, what they collect, what features they get etc.. plus any tell tale signs the machine did that went un-noticed can be very useful.
It happened a couple of months back. My mate and i were in a chip shop waiting for our food and he noticed a guy playing a little £25er in the corner. The guy pumped in about £10, kept getting on the board and losing, and my mate saw it flash, twice. We got our food and went back to the car which was just outside the door. The guy pumped about £5 more in, collected £2, got his food and went. My mate went back in, put in £4, and walked off with the JP, then it repeated and he got it again.
http://www.youtube.com/watch?v ... &feature=channel_page
You can be jammy though, just walk up to a machine to waste some time, press some buttons without really paying attention and just win big.
Knowledge does help, alot!
And having a refill key which tells you how full they are, and what they have paid is good too, and totally legal, just frowned upon, and will get you kicked out of places