If I have a Non-B multiple entry visa in my Hong Kong passport but don't plan to stay more than 30 days in a particular trip, could I use the automated clearance gates at either Bangkok airport and just get stamped in as Visa Exempt? Seems like I would never have the worry of getting hassled by IOs this way.
TLDR : Answer Summary
A holder of a Non-B multiple entry visa can technically enter Thailand using the automated clearance gates as long as they remain under the 30-day limit for a Visa Exempt Entry. However, it is important to note that using a Visa Exempt Entry means you are not permitted to work in Thailand, and the Non-B visa along with a work permit allows for work-related activities.