Dew point is the temperature at which air with its current moisture content would become saturated. If a surface falls to or below that temperature, moisture can condense on it. That makes dew point more useful than treating a relative-humidity percentage as a complete explanation.
The same room can have different surface temperatures at a window, external corner, wall junction or behind furniture. A room-air sensor does not measure every surface, but repeated air-temperature, humidity and dew-point evidence can help identify periods when condensation potential is elevated and where closer investigation may be useful.
A brief dew-point approach after cooking, bathing or drying clothes is different from a pattern that persists for long periods or recurs in one area. Indoor and outdoor context, heating response, extraction, room use and visible observations all help interpret what the pattern may mean.
Dew-point evidence cannot establish the cause of damp, prove a thermal bridge or replace surface-temperature measurement and inspection. It should support proportionate investigation and practical guidance, with limitations made clear.