There is usually a date to "use by..." on the package. Hot dogs do become slimy when old.
I'd check the best-before date, and if that doesn't help, trust your nose! It's true when they say that "the nose knows". Another tell-tale sign is that some foods, especially hot dogs, develop a slimy exterior, almost like a mucous. If that happens, chuck them out! "Marilyn" knows what she's talking about!
It's very difficult to tell if some food has gone bad just by looking at it, but there are definitely some "warning signs". But don't be thrown off by generalizing ..... mould is usually associated with foods gone bad, except in certain types of cheese. Mould on hot dogs, on the other hand, is definitely a no-no. Good luck.
Came upon this thread and wanted to offer another resource! I work at USDA's Food Safety and Inspection Service and am always referring folks to the fact sheet on refrigeration and food safety. Most importantly though, when in doubt PLEASE throw it out! Foodborne illness isn't worth the risk! Check out our fact sheet: http://www.fsis.usda.gov/Fact_Sheets/Refrigeration_&_Food_Safety/index.asp#13
This guidance is specifically related to safe storage of hot dogs in your refrigerator: Hot dogs Unopened package, 2 weeksOpened package, 1 week
they will feel slimmey and turn in color,and odor
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