So on trombone marketplace I keep seeing owners rating slide action 8 or 9 out of 10. Is there a standard for this rating system or is it an arbitrary impression?

It's not standardized by any measure. We talk about Ebay-speak where an 8 or 9 means you can get the slide to move with two hands pulling it apart. Some pros feel that an 8 or 9 means it's smooth as glass.

We were trying to get a grip on this thing with RobCat's slipperiness measure, where you measure how much dip the slide takes from pure horizontal to start moving. A good slide will start moving with only a few degrees declination while some student slides won't move if held completely vertical.

Also, a good slide with lousy lubrication will be slow. On the other hand, there is no lubricant that can make a lousy slide feel good.