I don't think anyone really minds you drafting as long as you communicate. I have has some bad experiences but mainly with men.

Recently I was riding home from work and got caught by a bloke on a long climb, he sat on my wheel up the climb and as I knew he was there I indicated pot holes, cars etc. Basically he knew that I knew he was there. At the top he put it in the big ring and went blasting past me, because it was unexpected and fast I didn't catch his wheel but shouted after him "oy thats not fair you can't sit on my wheel then sprint off without working!" I chased after him and caught him up and he was really labouring and down on the drops churning along, I sat there for a bit and then went round him to take a turn - trying to teach him some ettiquette - soon as I did that he pulled over and got off his bike. Weirdo.

Another time I was doing an mtb race called the Transalp, a group had formed on a road section and I was the only woman in it, when I got to the front of the line to work the man behind me sprinted past to the front to prevent me taking my turn. I thought he was worried that I'd be too slow to work. When I got to the back of the line he tried to take me out the back! (Its a roadie tactic for getting rid of riders - you sit up with the rider you want rid off on your wheel and drift backwards off the pace line, when there is a big gap you accelerate hard leaving the rider on your wheel with a big gap to close so they can't get back on the line.) He tried to take me out twice and I kept getting back on - after awhile I gave up. I was prepared to work but they clearly didn't want me there. Not often you get that though - most riders are happy to help other riders - I know it was a race but we were riding for like 300th place or something - not the win!!