Topbunk - I didn't think you were criticising and I am sorry if you thought it came over that way - I was pleased to be corrected and I opened the thread today to delete the incorrect bit (now done).
Unless it has changed, the way the system worked when I was around.
To ensure someone else gets what you don't want you need to make enough bids to make sure you get something you do want.
Suppose you are number 200 on the list (after you've discounted the sick, non bidders etc.) you must make 200 bids.
So if there are 250 lines and 50 of them you do not want then someone else will get one of them.
That means anyone who bids along the lines of any trip line or any blind line will get one of those 50 and not you.
Even if you are the bottom guy and you order all the bids you still stand a better chance of avoiding what you don't want as there are always those who forget, those who don't put enough bids etc., let them get the dross.
It certainly worked for me when I was a junior FO.
When I could change I chose a small fleet (Air New Zealand DC10) which had tailored bidline and worked to small fleet rules.
When I became a captain, I chose small fleets where I could hide until I was senior enough to get a decent bid.