In bullet & blitz, I don't mind my opponents rating (neither mine in bullet & blitz), so if you want to play me in bullet & blitz I'll likely accept. In classical, if you have tried to, it is very hard to find a suitable opponent at 90/30 using normal seek. Besides, that's not the way I do it (because of cheating problems), I usually thoroughly review profile before agreeing to a (classical) game. Sadly, even the people who play lots of 'classical' at something like 10+0 don't agree to 90/30 which is understandable. Oh, and for bullet I do something random like 1500+, all, bottom-1700, etc, since I don't really mind who I'm versing in bullet.
What I find funny about 90/30 is that people think it lures cheaters, but I don't think they'd agree to waste 4 hours for 10 rating points only to find out that they instead could have played 8 15 minute (or shorter!) games to earn something like 100-200 points, or more when a the person is a new member.
@DeathInTheToilet, that's totally fine. Many people (I think) probably use something like -300,+300. There's nothing not polite to other people by setting a low bottom, after all competing against higher competition helps for your opponent, and it is a double way agreement to play. Anyway -100 can still provide a tough challenge!