RS description of the Latin Quarter as a « tourist ghetto » makes me wonder how safe it is for a single woman in Paris for the first time.
Independently from RS, I too have previously written that St Germain des Prés and the Latin Quarter are tourist ghettos but if you assume that safety has anything to do with the word ghetto, you might check your dictionary for the definition of the word.
I´ll check the word ghetto for you:
A ghetto is a part of a city in which members of a minority group live, typically as a result of social, legal, or economic pressure
As it applies to St Germain des Prés and the Latin Quarter, the minority group in this case consists of foreign tourists who seem to congregate in these areas like moths around a flame. It has nothing to do with safety. Both of these areas, as is most of Paris, are completely safe. Probably safer than many hometown neighborhoods, even at night.
Perhaps the irony here is that RS, due to his popularity and loyal following, has turned rue Cler into what some might call an RS ghetto. It is because of an overabundance of tourists, particularly from North America, to these areas that I might recommend someone´s staying are outside of rue Cler, outside of Saint Germain des Prés, or outside of the Latin Quarter. Consider south of St Germain such as the area around Saint Sulpice or the area around le Bon Marché (which is some of the most exclusive real estate in Paris). Even areas in the 14th are very nice. Nothing wrong with hotels in the 2nd or 9th arrondissements.
There are numerous, wonderful locations to stay in Paris which are not on the well-worn, cliché tourist paths on the Rive Gauche. There can be great rewards and exciting discoveries to be made by trying something new, something different, something other than where everyone else appears to be staying.