Unfortunately, most plastics are useless to recycle - they either get incinerated or dumped straight into the landfill by the companies who collect and filter them.
Which is why my wife and I only bother with plastic bags, styrofoam, and the hard plastics marked types 1 & 2. These are the plastics which are easily recyclable, and therefore, have a non-trivial chance of actually being recycled.
We put types 3 through 7 straight into the trash, as they have about a 97% chance of not actually getting recycled.