Yes, hidden cameras should be used in data gathering. If you are data gathering you are trying to gather information without being detected and there is no better way than having hidden cameras. If people think they are not being watched they are more likely to show a lack of integrity.
Everyone should expect their activities in public to be monitored, whether someone is in public or in a business. Businesses have the right to monitor their own premises with or without permission of customers. However, hidden cameras in places like bathrooms are obvious violations of privacy. Everyone can expect to have their behavior watched no matter where they go outside their own home.
When you are gathering data for a specific purpose, it is extremely important to get accurate data. often times participants do not have the motivation to provide accurate data. Hidden cameras would ensure that all data that is collected is accurate and truthful. Although not a popular solution, I think it would solve a big problem to allow them.
The state and federal governments shouldn't use hidden cameras for data gathering against ordinary, innocent American citizens. Of course, these cameras are useful for sting operations against a specific target. However, they're unconstitutional when used in a random manner to spy on everyone that passes by in the camera's view.
People should be warned that when are on camera and should not be spied on because some may say that is invasion of privacy or something. Maybe it depends on why the data is being gathered and from whom it is being gathered from, but in general it should not be used.
I do not believe it is necessary to use hidden cameras for gathering data. Cameras are everywhere so these agencies that gather data could essential follow anyone in the world they wanted to, if this was allowed. While this may seem convenient, if they're attempting to follow a known terrorist, it's unlikely to be helpful, since those people would be aware of the data gathering. The problem with collecting this type of information and allowing things like this to happen, is it's not used appropriately. Governments are using to spy on other governments and corporations use it on consumers and the government. Whatever technology one group has, the other group is likely to have as well. Privacy has been dismantled because of governments need to monitor everyone. I don't believe it's right and I think some laws should be enacted to protect rights to privacy, rather that be privacy rights for other governments or individuals.
I don't believe that hidden cameras should be used for data gathering. Just thinking about it makes me think that there is something nefarious going on. If somebody is going to do something wrong, a camera ( hidden or not) won't stop them, they'll just figure out a way to circumvent.
When you have hidden cameras to collect data, there is a question of what data you're trying to gather and why the secrecy? This is a disturbing concept, because it strips away privacy, and that never is a good thing.