not in my experience. i've even had my initial settler spawn on a resource i can't see yet, and it's recommended that i settle there, and i've done it and regretted it later when i do learn to see copper or whatever it is. i don't have any saves of that tho. my current game i'm looking at 4 AI cities that are settled on top of resources, in 3 cases coal, the cities were founded before the AI knew steam power. does the AI settle cities where there isn't a blue circle?
i do know that barbarians know where unrevealed resources are. i'm often impressed with barb city placement, sometimes even more so after late-game resources are revealed. fun fact: barb animals are not allowed to step on tiles with
any resources ... dye, uranium, oil, cows, you name it. so if you're playing "come chase me, i want your exp but i really want to be on a hill when you attack" with a bear, and he just refuses to come at you, that might be why *giggle*.
edit: it definitely won't move blue circles off of resources if you add one to a blue circle it's already recommending, i just tested that in worldbuilder. i even hit enter to see if it needed a turn to register the fact that i'd sneakily added iron to that tile (i don't know IW). no change in the blue circle.
it will change blue circles if you change the terrain quite a bit. in the past hubby's tweaked maps for us to do duel-OCC games, and given us extra health resources. the blue circles move a lot during that process, even before you hit enter, just as soon as you leave WB the blue circle kinda bounces *giggle*. it seems to confuse the system, it wants to split the goodies into two cities or whatever. so i know it is capable of changing the decision once its been made. but it did not in this case.
it would obviously take a lot more time for me to find a situation where it's naturally giving me a blue circle on top of a resource and i'm not going to go to all that trouble
.