Have some very old sauces too, some are over 10 year and the have no mark of fungus or anything... use date , or best use date is far gone... But I thought to remember that Tabasco has to mature on oak barrels for 12 or more months, so in an airtight bottle it may last longer. Also here in Holland they even put a best use date on vinegar... For instance you can buy 25 year old balsamic vinegar... what is almost syrup... and pay a fortune... But I only trust hot sauces else than those on vinegar with a very long shelf life. Hot regards RobNL