The consistent theme here and elsewhere is that one has to be sufficiently self-assured to make a quick evaluation and have the ability to say "no thanks" when that's the answer. If you are offered something acceptable or better, take it. If you aren't and don't want to, just say "no thanks". No silly excuses or lies. Just say it.

Or if you want to be a doormat for others, just say "yes" and enjoy the middle seat near the lav.