I make a 10% bleach solution. I remove as much dirt and roots I can and then I soak my pots in a five gallon bucket for a week and sometimes up to a month. After that amount of time most of the bleach has dissipated, the pots are clean without even scrubbing and terra cotta calcium residues are mostly gone from the outside of most pots. The plastic pots can be rinsed and put away. Since terra cotta absorbs more, I rinse the pots out but soak them in water which gets changed daily for another three days to make sure anything in the terra cotta leaches out. I use terra cotta mostly for the orchids and succulents, it has not been a problem.
The old way to disinfect pots and plants was with Physan. It is a bench disinfectant, fungicide, virucide, and algaecide. While it is still available at agricultural suppliers it is really expensive.
I used it on the benches but it can also be used as a fungicide dip for orchids nd other plants. When orchids are repotted we often will dip orchids in a fungicide since they are very susceptible to fungal and bacterial rots. Unfortunately, orchid seed germination is dependent on certain species of fungi to succeed so the orchids do invite fungi and bacteria. However, not all fungi and bacteria present in a collection are the good kind, so the professional growers fungicide regularly. As a hobbyist, I just try to get by, so I lose a lot of my orchids in plastic pots, that is why I put most of the orchids in baskets or terra cotta.
P.S. It is o.k. to use cleaned pots on some plants. However, some plants that are especially prone to fungal, bacterial rots and viruses should always be in new pots whenever possible. Long term plants should be in new pots since they will be there a long time. Plastic pots these days are brittle and they don't last as long as the old pots.
Never reuse soil or a pot where the plant was virused. Viruses can remain viable on fomites. If you have a virused plants. Try not to touch it with your bare hands. Wear gloves; bag the whole plant pot and soil and dispose of it. Wash your hands after.
Tools should be disinfected after each cut or plant when you work on them. Orchidists use a small torch to heat the blade. Bleach and alcohol are other ways to disinfect tools between cuts, but they don't kill viruses. Utility knives with disposable blades is another way. People who have had to destroy collections and rebuild them have learned the hard way about the value of good sanitation.