Head towards Kiosk 4 on the Maspalomas or light house side of the dunes as opposed to the one on Playa del Ingles side. The area of scrub a couple of hundred meters inland is used by gays behind that it is mixed couples. I've never really seen anything going on other than a couple of men on the edge of the gay area. All of the area behind the sea front gets a little off putting by the number of 'meercats' looking for any hint of action or just plain wankers that are likely to put the pair of you off.
But don't be put off visiting, it really is a great atmosphere around kiosk 4 which if you didn't already know is the nudist area.