it can depend entirely on the employment agency and/or the employer who may have given strict guidelines to the agency
some will access all of your social media to see if you posted something that was not politically correct and if they find just one from 10 years ago, who knows if they will let it slip or not. they have more than enough applicants to pick and choose based on such things as when your dog last had it's shots. the positive with that is that they will also most likely pick up dirt on every other applicant they vet as well
while no one in their right mind would sack someone just for being unhappy, sadly this world runs by mob rules/union bs, and if people do not like that someone is unhappy, they might very well join forces with others, put their foot down and give an ultimatum to the boss and then there may be trouble. the other thing is, that there is a chance that being unhappy does interfere with someone's ability to do the job properly and therefore, while being unhappy was the catalyst, it is not the real reason for dismissal. in the end, the result is the same, but both the employer and employee have valid reasons to look at it from their own side
every single thing someone puts on the net is 100% traceable (except child pornography, trafficking, the dark net etc.. you know, the things that really matter :( ). you just need to know where to look for it. if a very young man in manila can get the pentagon and cia to shut down over one simple email or another 15 year old kid from america can hack into nasa, then looking into social media is child's play
a prospective employer may not care if someone is on here. most people do the bare minimum they have to at work anyway, so why would an employment agency worker do any more than the average person, but a sad fact for the younger generation, is that they do need to be very wary of what they post, or even what they take pictures and video of. when i was a kid, we could do anything we wanted. nothing was traceable unless someone actually saw or heard us. we could take the most explicit pictures of ourselves and they would just stay in the camera until the film was thrown out for being old because we took too long to go and get it developed by the family friend in the photo lab. now, take a picture of yourself, and it is already out in the world waiting for someone to stumble across it and look at it and maybe share it online. people need to be very careful and think hard about what they document, because while most of it will never be found, so of it might be
but once again, scared cutter is probably fine due to the australian laws regarding this site. people from other countries are potentially not so lucky - but, considering no one is normal or truly sane, perhaps no one who vets a potential employee really cares if someone is on here and they almost certainly do not care enough to look - but; be careful. once it is on the net, it can never be removed