Creep - To slip out of place; shift gradually (Answers.com)
Recipe Creep - The process by which a recipe changes gradually over time until at least some variations bear little or no semblance to the original recipe
Example 1 - Vichyssoise
The cafeteria I go to most often for lunch served vichyssoise (pronounced VEE-shee-swahz) last week. Their 'version' was cold leek and potato soup with lumps of potato, bits of potato skin, bits of spring onion, and lemon flavoring. The lemon flavoring was suspiciously artificial tasting and made the whole thing taste vaguely like a lemon creamsicle!!!
Now I will admit that I tend to be a traditionalist when it comes to food, but to me vichyssoise is a rich, smooth soup made from leeks and potatoes, with absolutely no chunks of anything. The color is nearly snow white. In order to achieve that whiteness, only the white portion of the leeks get used, and they are sweated, taking care to not allow even a hint of browning. Then a white stock or light colored chicken stock is used, too. The only color, traditionally, is a garnish of minced chives.
According to Julia Child et al in Mastering The Art of French Cooking, Volume One, once the soup is cooked, it is puréed in a blender or food mill and then passed through a fine sieve to remove any solids that may be left.
No other vichyssoise I have ever tasted had any lemon flavor.
Example 2 - Carpaccio
Carpaccio (pronounced car-PAH-chee-o) is made with very thin slices of raw beef, drizzled with olive oil and lemon juice or served with a mayonnaise or mustard sauce and garnished with capers and sometimes green onions. I have seen it served with a mimosa made by pressing cooked egg yolks through a sieve. Carpaccio is credited as having been served first at Harry's Bar in Venice, Italy.
More recently, concerns about the safety of serving raw meat have scared off many restaurants from serving carpaccio in its original form. A while back, I ordered carpaccio at a bistro in Regina, Saskatchewan. What came out was a piece of seared tenderloin, cut crosswise into 1/4 inch (6mm) thick slices and napped with some nondescript tarragon based dressing. The waiter assured me that this was THE ORIGINAL recipe!
Nowadays, you hear of tuna carpaccio, melon carpaccio and any number of other variations. I may forgive tuna carpaccio as being at least somewhat similar to the authentic recipe, but if you slice your radishes thinly, then call them thinly sliced radishes, not radish carpaccio!
Recipes may wander due to health reasons, as with the carpaccio, because a chef thinks that they need to put their own impression onto a dish, because of availability of ingredients, or for any number of other reasons, but at some point you need to honestly step back and say that a recipe has crept enough and that it no longer warrants the name. Cold lemon creamsicle potage parmentier is not vichyssoise!
There. Now that I got that off my chest, I think I'll go open a bag of Sour Cream and Onion Confit of Potato Carpaccio.