Lots of different types of home canned foods benefit from being wiped clean after the bands are removed from the jars and the seals are tested. And all home canned foods benefit from a date and labeling the contents.
Very often the outside of a home processed canning jar will be sticky or greasy. That’s because during the actual canning process most jars will vent a little allowing some of the contents of the jar to escape.
It’s one of the reasons that sometimes fluid is lost in a jar during processing and is the reason that it is important to maintain a proper “head space” for the particular food product that is being canned. Too much or too little head space can result in a loss of liquid and failure of the jar to seal.
After canning I always wipe my jars clean with warm soapy water and label and date them. A clean jar will not grow fuzzy mold in storage or attract rodents. Large rodents can and will take the lid off of a canning jar.
In a cool dark root cellar or basement, mold will often grow around the threads of a canning jar that is left sticky or dirty. Mold can make its way from the jar threads, to the rim of the jar, and under the lid and cause a lid to pop off and a seal to fail.
Labeling and dating the contents of a jar makes for an easy inventory and food storage rotation.
Not to mention that labeling helps to distinguish food that appear similar – like cranberry sauce and cherry jam.