In Thailand they generally don't use salt at all. If you go to a real Thai town where there are no farang, then you won't be able to find a jar of salt. They just use fish sauce, which is naturally very salty. This is why the don't give a shit if the salt is blocked or not, because they only put it there for the farang.
you could put some rice corns into the shaker. The rice should absorb the moisture
I am not sure why you think they do not use salt, but they sell it in every store. I just ask Dai about this, a Thai girl my friends Mr. Joes Travel Agency, she read the post and laughed. I will write a good friend of mine about the salt and collaborate more.... BUT
SALT IS EVERYWHERE IN THAILAND!
They use salt.
This is the most common solution.
Note that I have traveled for 8 year, I have salt in half my salt shakers. This does not work, it only makes it more difficult to use the salt.
I take the salt lid off, pour a little salt in my hand. Then slowly use my index finger to push the salt onto the food.
The problem here is a caring problem and for most any country. The salt shaker I was using only had one hole, that means even the rice would block the hole.
The Arabs are more pratical they just put a bowl on the table with salt. I have seen some pepper grinders that I think I could used to grind the salt out the shaker. The tropics is not the same as a western country, the moisture is very high, this is winter here in Thailand and the moisture is low. In the rainy season this would be way beyond rediculous.
Both of the above replies do not work, there are two problems.
1. Getting underdeveloped culture to care about quality.
I was in a VERY expensive hotel for Khao San Road.
2. Find a new type of salt shaker. The rice is not a solution for a real moisture problem.