Can you use vinegar to verbs suede? ...

Whats the best route to return with stains...
Answers:    No. Water, vinegar are both liquid. It will walk off a 'water stain' and except dried properly, flatten the fibers.

If have recent rainfall spots, brush them out.
If have stains from milk, beer or unprepared egg, it is permanent.
If fibers flattened, they will not straighten.

Take to cleaners. Hint: Tell them you want a 'Clean Only'; singular 'pressing' is lightly to the inside layer. Worked on suedes for years & at dry cleaners.
Clean the toilet??
No.