A few days ago, I witnessed one of the clumsiest back counting techniques. A guy was standing behind the players, obviously making efforts to see all the cards dealt, by constantly moving left and right. At one point (it just so happened that the TC was between +2 and +3, lol), he started waving to another guy, who was a few tables away. This other fellow rushes to the table and starts betting the 2 open spots, for about 3 or 4 hands, until the count goes down to below zero. Then he gets up and leaves the table.
These two guys went through the same procedure a few more times. The guy who was doing the counting wouldn't leave the table, just stood there, but never played. He was only moving between 2 or 3 tables. And when the count was favourable, he would be literally waving the other guy in, who would then play until the count goes down to minus.
It was so obvious, that I couldn't believe these guys were even thinking of doing it this way. But I guess, if it works, why not? The question is for how long?