Playing league mostly in bars on tables in less than stellar condition, in order to get a consistently tight rack I use the following technique. I first place the 1 ball on the spot (or as close to center on the spot that any divot will allow). I then set the rack in place so that the 1 ball is locked in this position. I then build the rest of the rack behind the 1 ball while holding the rack in place to keep it from moving.
This is the only way I have found that I can consistently get a tight rack for my opponent, yet I get questioned about it quite a bit. People will inspect the rack, see that its tight and still complain. I would like to get other's opinions on my technique and how/why they choose to rack the way they do.
I'll have to remember this next time I'm playing league where the tables are rough. Pretty sweet idea if you ask me and I certainly wouldn't complain.