It would be lovely to think that 'genuine' employers, seeking new recruits, would scour through online CVs, looking for suitable candidates.
The reality, however, is that they simply don't. The only employers that search through online CVs are those that are looking for mugs, whom they find difficult to attract through conventional advertising. (Double-glazing and 'home improvement' firms are among those that regularly contact people who've posted their CVs online).
I'd always be wary of such firms but, as I've indicated above, you might decide that it's worth trying it for a few weeks (as long as you've decided, in advance, when you'll make your 'stay or leave' decision).