I'm sure most people will have noticed that some of this years grid references pass close by bothies. They tend to be interesting places in great locations ... which is the main reason they're on the list. That doesn't mean that you can't use the odd one though.
If you are planning on staying in any bothies then (in my opinion) I think it's only reasonable to give something back to there upkeep. You can do this by joining the MBA who look after most of the bothies in the UK (there is a bothy on the list which isn't looked after by the MBA). It doesn't cost a lot to join and besides helping maintain these fantastic places you'll also get a magazine 6 times a year which is really very good.
If you've never been to a bothy then it would be well worth taking a trip to the MBA website http://www.mountainbothies.org.uk/ and have a look at the bothy code. Most of it is common sense / good manners but it won't do any harm to look.