I'm level 70 slayer and I'm getting tasks that give bad xp/loot.
I think slayer tasks should have a cut off point from when you stop receiving certain tasks. So like at level 60 slayer, one should stop receiving rockslugs, just as an example. It would give people more motivation to do tasks if they knew they wouldn't be given bad tasks anymore.
Lower-level Slayer sucks, once you unlock Nieve/steve you don't get assigned those monsters though. Also, there are block options you can use. you might wanna do a little more research before hopping on the forums