Tolerance is one thing "receptors blocked" is another. There are indicators in the consumption of both compounds in our body. While serotonin is being processed by our brain, we have positive feelings, happier outlook and so forth. With Capsaicin we feel a burning sensation in the receptors that are exposed to the compound.
In a person without the natural production of serotonin, we would notice a marked decline in mood once the dose of serotonin fades. In capsaicin we do not produce this naturally, but when our exposure to it is waning, we have a decrease in the pain in the exposed areas (mouth, throat, stomach, etc).
Its like a car that has a flat tire as they are entering an expressway. They may plug up the on-ramp for a minute, but once the tire is changed traffic once again flows freely.
That said your brains sensitivity to the pain response delivered by the same stimuli decreases over time.
If a certain intersection always has an accident (frequent repeat exposure), then you learn to drive using alternate routes, decreasing the experience of exposure to bad traffic from that intersection.
With peppers you will still feel the heat, but your brain adjusts the level of stimuli required to trigger the pain response mechanisms...