Went for a spottingtrip to Madrid's surroundings (Getafe, Torrejon, Colmenar) last Octobre. General attitude towards spotters variates.
First of all, scanners are forbidden.
At Getafe we were quickly sent away from the maingate. While driving around the airfield we were passed by the police who didn't take notice at us at all. Half an hour later we were actively spotting with binoculares and noticed a policecar wich was looking for a way to get to our position. We quickly moved by foot through a shortcut to our car and left.
At Colmenar we were visited by the guardia civil. They checked our pasports and camera's. Taking pictures wasn't allowed and the place where we were standing (according to the Scramble guide a great place). This turned out to be a kind of park wich only could be entered by some locals to harvest mushrooms. Yes, the guide's right ... that place is perfect for spotting at Colmenar, but in the end not suitable due to local regulations.
At Torrejon we were visited by the local policia. We were standing just on the bourder of where the military jurisdiction ended (somewhat 400 meters from the fence). Taking pictures of planes wasn't a problem, as long as we didn't take pictures of or towards the base. Nice fellows, those local policia. We had a half an hour talk with them, wich ended in this cool picture (made by the other policeman ... towards the base
):