The obviously bad part is that you pollute the global namespace for no reason other than laziness. When someone comes across code that uses a "Table" object int

The obviously bad part is that you pollute the global namespace for no reason other than laziness. When someone comes across code that uses a "Table" object interchangeably with "Dictionary" and "Hash", then he's going to have to look through the source code to find this bizarre line only to find out that you renamed a built-in container for no good reason.