I don't remember whether I posted this story earlier....
When we moved in, the toilet in the master bathroom had a funny property
: after it was flushed, the cistern did not fill back in until the tap of the nearby basin was opened. Not difficult to guess something in the cistern's valve was slightly stuck so when the basin tap was opened, it changed the water pressure in the pipes and gave the valve a kick already good enough to get it working.
As it was still under the initial move-in 30 days warranty period the LL's agent arranged for a plumber to visit. The plumber arrived, was introduced to the problem, the workaround and then, without any hands-on checking, he gave me his verdict: it is like this, because this is an American Standard (the name of the brand) toilet. I looked at him and started laughing. When I got a grip on myself I told him, this is not the first AS toilet I used and apparently all the other AS toilets did not have this interesting property. More-over, I took him to the guest bathroom toilet, also AS, working fine. He tested it by himself flushing it few times. It didn't convince him. He went back to the master bathroom, opened the cistern and proposed to replace the whole valve (the complete internal column) for $250. When I said I was not going to let him do it even if the LL would pay for it, he put his hands inside the cistern probably looking for the overflow holes, because when he finished he suggested to partly block the holes with epoxy.
I though this was probably already enough so asked him to put everything back in place what he did still trying to convince me to one of the proposed solutions. When he finished I pressed the flush button to check whether he did not #####-up something more seriously. The water flushed and to my surprise the cistern started to fill in as it should without any extra kick – yes, the guy just moved/bent the valve column when he squeezed his hands between it and the cistern's back wall. I had a good laugh for the second time that day. The plumber was slightly confused or maybe even embarrassed but not to the extend to cancel his on-site visit expert examination fee of $40. The toilet works fine till this day.