It is free, unbiased (lots of the specifically tailored sites like PA mentioned above have affiliate deals which reduce the amount you can earn) and active.
Discussion on the MSE forum is restricted to what they define strictly as "risk free", not "EV+" opportunities, but that's a healthy start.
Their definition of risk free is making a guaranteed profit regardless of the outcome - Either natural arbitrage or an offer-dependent forced arbitrage.
http://bonusbagging.co.uk looks like a scam website, but I know a few people who have done it, myself included.
There is an upfront time element needed, and then to keep it rolling you'll need to take advantage of reload offers if you want a trickle, but if you're prepared to put the work in and use a site like this that does most of the "thinking" for you, it can work.
That website reminded me of parrotsecrets.com made & written about by cringely [1]. It is designed to slowly increase excitement in the reader as they progress through the page (that's why it repeatedly insists you slowly read the whole thing instead of skimming) as it leads them towards a sale.
a guy I know very well does websites like this. He uses a bit more tech behind it with bandit algos etc and nets 1 to 2 million a month. He has been at it a good number of years now.
That home page is awful even by the standards of actual scam websites.
I remember the now defunct site that showed me how to bag bonuses as a student a decade ago being straightforward about your pretty modest level of expected winnings (and for blackjack bonuses, modest level of risk) and focusing mainly on the actual maths.
For anyone that wants it as a passive income project, there's some very nice potential affiliate earnings (redirected through another domain, naturally) for anyone that wants to create a less scammy looking explanation...
Either he means exploiting bonus programs for new members, which is hardly sustainable and unless there's an endless supply of those. Or it's your regular arbitrage gaming, which is also hardly worth the effort and not free of risk. If it's an arbitrage scheme in an exchange, where the quotes might vary over time, your are gambling and at that you are probably playing the bookie who always has the better latency.
There are various sites such as oddsmonkey that do a lot of the effort of finding price disparities for you, so you can arb with confidence.
Regarding bonus arbing, as long as you don't get banned lots of places perform regular stunts with free bonuses for inactive accounts to try to drag punters back in.
(Disclosure: I work for an exchange)
"arbitrage scheme in an exchange, where the quotes might vary over time" - The nature of arbitrage is that the profit opportunity is available at a single moment.
What I interpret your explanation as is more akin to trading - Buying backs at a time and waiting for odds to fluctuate at an exchange for a sale.
Although there is no (simple) way of doing a pure arb between a bookie/exchange, all the popular exchanges expose existing liquidity in a market and you can quite safely reduce the risk by double checking available liquidity at the exchange in the seconds before placing your back bet.
It's a combination of both. Initial signups is not sustainable, for sure, but there are some regular offers from a lot of bookies that are exploitable not for guaranteed profit, but "EV+" opportunities. This is where my consistent side income comes from.
If you're interested I highly recommend the MoneySavingExpert Matched Betting forum - http://forums.moneysavingexpert.com/forumdisplay.php?f=41
It is free, unbiased (lots of the specifically tailored sites like PA mentioned above have affiliate deals which reduce the amount you can earn) and active.
Discussion on the MSE forum is restricted to what they define strictly as "risk free", not "EV+" opportunities, but that's a healthy start.
Their definition of risk free is making a guaranteed profit regardless of the outcome - Either natural arbitrage or an offer-dependent forced arbitrage.