Just do it. Thanks. It's simple and funny. Yet powerful
1- you did not read the T&Cs of each site.
2- you did not understand them properly.
3- you don't understand those who implemented it, didn't. (Understand and/nor implement properly!)
Ergo: add your own salt to your recipe!
For the geeks: 26^15=circa 1.7 times 10^21 (circa 1.677.259.300.000.000.000.000 combinations) which is 2^71 in other words 70+ bits of entropy in the password strength
Crypto wise, any case salt is quite significant. (2^15=circa 32k variations) on 70 bits password. BUT if your password is published or known, change them all (32k variations IS brute-force-able GIVEN the original clear-text....