The problem may be in the meter that you are using. Some of the really cheap meters are known to have a lot of inaccuracy. For example, many will corrode quickly over time, and as a result, will give a false reading. Another issue is that many of the cheap meters are affected by salinity (i.e. fertilizer). In this case, the salinity will also give inaccurate readings, saying that your soil is more wet than it really is. Now this doesn't mean that all meters are bad. Essentially, you get what you pay for. I am currently using this
soil moisture meter and it has worked very well for me. Rather than giving an obscure number, it displays moisture as a percentage, with 0 being no moisture at all. It also doesn't corrode and isn't affected by salinity (which for me is a huge plus). Although it cost more expensive than the cheap ones, I have been extremely happy with it for the 3 years I have had it.
If you don't want to put down the money for a better sensor, here are some alternative options:
1. Stick a finger or piece of bamboo in the soil. If it comes up dry with no soil stuck, it needs water.
2. In the case of potted plants, you can either kick the pot or lift it. You will get a feel of how heavy it should be when watered.
Whatever you happen to do, hope you found this helpful!