As someone who probably bets more than they should - and regularly uses bet365 - i'd like to try and re-assure folks that the bet365 offer is no scam and that there are genuine (and undoubtedly profitable) motives behind these free bet offers.
Please don't be deluded and think it's only a matter of time "before they catch on".
The reality is that for everyone who places a "no lose" combination of bets, there are probably 10 "regular customers" who use the risk free bet on the off-chance they can make serious money. Most will lose, some will win, but the bookies will have succeeded in attracting enough pre-match "qualifying bets" to make a significant profit. They will also attract a large number of people to open new accounts to take advantage of the offer, many of whom will start to use these accounts regularly.
So if its a no-lose bet your after, fill yer boots !
p.s. there are however a couple of things to watch out for, which aren't made explicitly clear in the promotional emails.
1) qualifying pre-match bets must only be single bets (not accumulators), otherwise your in-play bet won't be risk free.
2) if you cash out your pre-match qualifying bet at any point, your in-play bet won't be risk-free.
The strict t&c's are simply to cover their backs. I've been caught out on both points before, but argued that the promotional emails i'd received had specified nothing about cashing out - or single bets only - and got my in-play stakes refunded as a "goodwill gesture". Worth bearing in mind if you do get in a position where you don't receive your refund.
So go for it and good luck ! (Barca to lift trophy and Barca -1 in-play for me).