Clearly none of these people (hosts, guests) have any idea about basic communication.
"Can I bring anything?"
"Yes, please bring (a half gallon of x or two pounds of y)."
"Do you have any allergies or special dietary requirements?"
"Yes, I'm allergic to nuts," or "I'm on the South Beach Diet."
"Oh, the South Beach Diet. Aren't there some nice individual frozen meals suitable for that? Please bring enough for yourself, I'll be preparing food for the rest of us."
Clearly ditching the friends (or the house in Tuscany or wherever) would not solve these people's problem--they'd still have to live with themselves:-)
A dear family friend, one of my mother's closest friends and a kitchen soulmate (after my mother's death, she requested a pot from Ma's kitchen as a keepsake:-) is a cookbook author (and technical writer of recipes for some well-known cookbooks, including Bayless's first and The Harry's Bar Cookbook, which got her flown to Italy several times, including once just to prepare the dishes during truffle season).
Her first cookbook was written to cover cooking for second homes with houseguests. Published in 1974, "Cooking for Carefree Weekends" provides weekend menus using fresh and seasonal ingredients, that are surprisingly contemporary. Having been both a guest at many weekends at her house and a willing kitchen helper, I can personally attest to the value of the recipes.
Used copies of the book are available on Amazon:
http://www.amazon.com/COOKING-CAREFREE- ... B000G1MCYK
For those who have a second home, it provides both good recipes and clear thinking about how to approach the situation. Having been fortunate enough to have possession of my in-law's cottage in Wisconsin about 48 weekends a year for 10 years, I know that it can, indeed, be a challenge. I was grateful at the time to have read this book.