Don't know your field but I think efinancialcareers.ch is pretty good if you have skills they need in banking. Some adverts are from recruiters but some are directly from employers.
you should look at the career sites of the companies directly (in the sector that you are interested in), all sites such as jobup.ch, indeed.ch, topjobs.ch do not have a lot of direct jobs
www.direct-jobs.ch is one site where there are jobs from employers. The catch is that you need to register. First five days are free but after that you need to pay. Its genuine though.
Most recruitment companies are bollocks, but there are a few that know what they're doing and will actually help you get a job that you want with better conditions too sometimes! One company I know of, Stamford Consultants, specialises in IT. I would contact them or check our their website for their vacancies, I don't think they put in fake jobs as they all seem to be individually-written postings etc. :-) Best of luck!
Indeed the recruiting agencies take old postings from last year and repost them now. You will go have an interview with them and then find out that there is no job, they just want you on their "roster" in case that job gets open again so they can refer you asap and get their fee. After a while of searching you should start to see a trend. At one point I saw 4 different recruiting agencies recruiting for a position at JP Morgan which didn't exist.. JP Morgan was not hiring and had no plan to hire.
I've received quite a lot of interest from that site and linked in... but its been from London and USA (usually east coast such as New York, Connecticut etc but once from Dallas).. so far nothing in Switzerland.
Edit: Just remembered: I did have one contact me from Zug from efinancialcareers
For LinkedIn I've found the best luck by joining groups in your field and posting in those groups with a brief outline of your experience and the area you are looking. Every time I've done that I've received some interest. So far nothing local but it still feels good to have people call you and try to talk you into moving
I would look directly on the potential employers website in career section.
It works only of you are familiar with the potential employers here . which would be difficult if you are new here .. but I think this is the best way to find some some good opportunities.