If I understand correctly someone with 500 post is twice more affected by ignores than someone with 1000 posts ?
Not quite. For every 500 posts, one of your ignores is not counted.
user established_ignores ignore_ratio posts adjusted_ignore_ratio
smoothie 116 .06505 5482 .05947
zyk 105 .05888 400 .05900
Atlas 70 .03925 934 .03877
bulanula 70 .03925 2947 .03651
subSTRATA 60 .03365 46 .03416
MPOE-PR 56 .03140 2455 .02921
ElectricMucus 56 .03140 3952 .02753
cunicula 54 .03028 1811 .02881
Maria 52 .02916 404 .02927
Rarity 50 .02804 814 .02769
lucif 47 .02636 1086 .02570
sublime5447 45 .02523 527 .02520
becoin 45 .02523 628 .02509
Micon 44 .02467 861 .02427
bonker 43 .02411 321 .02431
Matthew N. Wright 41 .02299 6237 .01655
MeSarah 41 .02299 159 .02337
bitlane 37 .02075 2334 .01869
Are heavily ignored people removed from established_users ? That would act as a safety mechanism.
No. I'm not sure that there's a link between being ignored a lot and having a "bad" ignore list.