French people do say oh là là, hou là là and houlà quite often but it doesn't have the connotations found in English. Well, it can but rarely.
Here are examples of its use in French:
Il est déjà sept heures. Hou là là, je vais rater mon train !
Houlala le train, il est en train de partir !
Oh là là, elle a repris du gateau !
Hou là là, il a dû se faire mal en tombant !
A reason explaining the popularity and oriented meaning of this expression in English might be Fifi D'Orsay, actress and singer born in Montreal who made all her career in the US and who made hoo-la-la her trademark according to several sources.
