Which of the following is a non-issue when performing services on children?

Speaking directly to children in a comforting tone is a positive practice when performing services on them. It helps create a relaxed and friendly environment, making the child feel more at ease during the service. Establishing rapport through gentle communication can alleviate any anxiety or fear they may have about the process.

The other choices are concerns that need to be taken into account. Using intimidating tools can frighten children, leading to a negative experience. Considering a child’s emotional state is crucial, as they may react differently based on their mood or prior experiences. Making assumptions about their preferences can lead to misunderstandings, as children's likes and dislikes can vary widely and change frequently. Thus, it's essential to engage with them directly and respectfully to understand their individual needs better.