Ok got to have my little go haha!!
I do not tolerate selfish people, if i see all the sunbeds reserved anywhere i go and no people laying on them then 2 towels get removed wherever i want to lay.
If i see a towel on a lounger that has belongings there, ie book, flip flops, suncream etc etc thats obvious its being used, but if all the others are just a towel, no belongings then its obvious theyre off out somewhere and are not actually using the bed, this is my cue to do as Terry says, remove them!
If the owners of said towel come back and start questioning you about moving their towel just say 'were you here laying on it, do you own this sunlounger' the answers will obviously be no so your reply is 'well there you go then' and then proceed to carry on reading or lay back down and sunbathe, they will be left standing there embarrassed!
If youre not going to be laying there you cant reserve the sunlounger, simple as, they are for people who WANT to lay there at that specific moment, not who MIGHT want to lay there later, ridiculous.
I also agree with the drinks thing, we always return empties to the bar as we're normally getting another round in at the same time haha!! But as you say, its manners, and luckily myself and Brett were brought up with those!