Two incidents regarding the Guardia Civil spring immediately to mind. The first was in 1998, the night England got knocked out of the World Cup against Argentina and Beckham got himself sent off. My mates and I watched the game in the restaurant in the Florida Hotel just by the egg and the four of us then trudged off towards the West End to drown our sorrows. We got to the bottom of the main drag and it was crawling with Guardia Civil. There were four large 4x4 off road vehicles, a couple of cars and a couple of motorbikes. The officers appeared to be heavily armed and ready for the slightest hint of trouble or step out of line. We were sufficiently intimidated enough to go and seek drinks around the bay but their tactics must have worked because there were no reports of any trouble whatsoever.
The second thing happened about fifteen years ago (I think). It was before Bar M was Bar M. My mate and I had agreed to meet some other friends there and so we sat having a leisurely afternoon beer. Across the road is a patch of land used as a car park and the Guardia Civil had parked up in there and were directing cars in to do random stops, checks and searches. My mate and I noticed one of the officers suddenly stride into the middle of the road and put his hand up like an old fashioned policeman directing traffic telling it to stop. This young kid and his girlfriend on a scooter tried to swerve around him but he reached out and hooked the girl off the back, dumping her on the tarmac heavily enough to wind her slightly I guess but not hard enough to do her any damage. He stood over her giving her a fearsome bollocking and gesticulating that she should be wearing a helmet. Meanwhile the boyfriend had laid the scooter on it's side in the road and ran back towards the officer effing and jeffing at full volume. At this point a second officer ran out of the car park at full tilt with baton drawn and hit the lad so hard on the leg it swept him completely off his feet and hit him a further couple of times on his arm/side. My mate and I decided at this point we didn't want to be noticed by the officers that we were watching as we didn't want any unnecessary grief so we moved away and sat with our backs to them (we were both carrying and I had a large lump of beautiful freshly made Jordanian hash that I didn't want to have to hand over if they decided to search us). I also quickly texted my friends on my good old Ericsson house brick to tell them to dump anything they were carrying or park much further away.