A clean ass is a good start.
I don't know what you've got to do polish that thing, but, it's the bottom line, if I'm going anywhere near it. Your butt should smell and taste like candy, when I roll you over.
And gas--get rid of it all, before we go at it doggy style. I know a woman, who could set your sheets on fire. I mean the bedroom's uninhabitable, when you get her going - even with a little fingering. [Great sex, otherwise though.]
Certain foods can make the butt an unfriendly place, when you're poking around back there. Cheeses (pizza, macaroni & cheese), beans, steak and pork should be avoided, when you want to get down with your woman. Even potatoes in large quantities should be scratched off the menu. Anything that creates gastrointestinal action is a no-no.
Instead, grab up something healthy: fish, roasted or baked chicken, soups or curries and salads, of course. These foods are anal-friendly,
whether you're doing anal or just going at it, doggy style.
I think there's a website out there with all this info. I can't remember where I read it or heard it, but wish I'd known about it a long time ago. Has anyone else read this stuff about sex-friendly foods?