Return proposal is to judge the projects that deserve funding, in general proposals going above the return proposal are funded (except if projects even higher take all the daily funds).

In a case of SPS used for polling, the proposal should not compete with the return proposal but with another proposal tailored to this purpose.
P1 : We should HF to remove the free pool of downvotes.
P2 : We should not remove the free pool of downvotes.

It s a bit more expensive to put in place but its the only fair way to measure the community support.

EDIT : To go further, the different proposals should start and end at a predetermined and identical time to be absolutely fair.