Better way to rename files based on multiple patterns

a lot of files I download have crap/spam in their filenames, e.g.

[ www.crap.com ] file.name.ext

www.crap.com - file.name.ext

I've come up with two ways for dealing with them but they both seem pretty clunky:

with parameter expansion:

if [[ ${base_name} != ${base_name//\[+([^\]])\]} ]]
then
    mv -v "${dir_name}/${base_name}" "${dir_name}/${base_name//\[+([^\]])\]}" &&
        base_name="${base_name//\[+([^\]])\]}"
fi

if [[ ${base_name} != ${base_name//www.*.com - /} ]]
then
    mv -v "${dir_name}/${base_name}" "${dir_name}/${base_name//www.*.com - /}" &&
        base_name="${base_name//www.*.com - /}"
fi

# more of these type of statements; one for each type of frequently-encountered pattern

and then with echo/sed:

tmp=`echo "${base_name}" | sed -e 's/\[[^][]*\]//g' | sed -e 's/\s-\s//g'`
mv "${base_name}" "{tmp}"

I feel like the parameter expansion is the worse of the two but I like it because I'm able to keep the same variable assigned to the file for further processing after the rename (the above code is used in a script that's called for each file after the file download is complete).

So anyway I was hoping there's a better/cleaner way to do the above that someone more knowledgeable than myself could show me, preferably in a way that would allow me to easily reassign the old/original variable to the new/renamed file.

Thanks