I don't think it's that all bacterial products are 'bad' - it's that in a cycled tank, they aren't necessary.
If you need to add them with every wc to keep your tank cycled, it isn't truly cycled and can very quickly become unstable.
I haven't used these products myself, but from other posts here the only bacterial product that works (for accelerating the real cycling process, not for regular addition to keep it cycled) is Tetra Safe Start.
See this thread, it's related and may help answer your question:
Bacteria Supplements
Good luck!
Edited to add: this may be of interest too -
My Experience with Superbac Nitrifying Bacteria