CS5.5 was dropped entirely from Adobe support on 1/31/2014 and was never supported past 10.6 but I guess Apple doesn't bother to check Adobes website that lists the OS CS5.5 is supported in when the recommend the answer they choose.
I have deployed CS5.5 to about a dozen production Macs for a number of designers and even on clean builds the program can be far more unpredictable outside of the OS's it was slated to be used. Photoshop appears to be the most stable but InDesign and Illustrator can be finicky even with clean installs, full patches and the required 2015 Apple Java. Everyones issues are not the same and CS5.5 may work flawlessly for some users who's workflows do not require functionality that doesn't work for others.
Using the Adobe cleaning tool in conjunction with a new administrative account is one way to try and correct anything that might be correctible. A clean build of any OS past 10.6 and a clean install into an admin account is another way to present a platform with the best possible stability outcome with these unsupported products.
Adobe states on their website CS5.5 for Mac works in 10.5.8 or 10.6. It was never QC'ed by Adobe past those iterations of OS X and much of the framework for OS X appears to have changed considerably after 10.6.7.
Your milage may vary as one of my MCSE instructors loved to say.