Spotting an ISTJ (Introverted, Sensing, Thinking, Judging) can be done by observing their behavior, preferences, and characteristics. Here is a detailed description of how to spot an ISTJ:

1. Introversion: ISTJs are typically reserved and prefer to spend time alone or with a small group of close friends. They may appear quiet and thoughtful, often needing time to recharge their energy by being alone. They may not actively seek social interactions and may prefer to observe rather than participate in group activities.

2. Sensing: ISTJs are detail-oriented and rely on their senses to gather information about the world around them. They pay close attention to facts, details, and practical information. They prefer concrete and tangible experiences rather than abstract concepts. ISTJs are often focused on the present moment and may have a strong memory for specific details.

3. Thinking: ISTJs make decisions based on logic and objective analysis rather than emotions. They value rationality and fairness, often seeking to find the most efficient and effective solutions to problems. They may appear detached or unemotional when making decisions, as they prioritize logical reasoning over personal feelings.

4. Judging: ISTJs prefer structure, order, and organization in their lives. They like to plan ahead, follow schedules, and stick to routines. They are often punctual and reliable, valuing responsibility and dependability. ISTJs may have a strong need for closure and may feel uncomfortable with ambiguity or uncertainty.

5. Work Ethic: ISTJs are known for their strong work ethic and dedication to their responsibilities. They are often diligent, thorough, and committed to completing tasks to the best of their abilities. They prefer to work in a structured environment with clear expectations and guidelines.

6. Attention to Detail: ISTJs have a keen eye for detail and are often meticulous in their work. They are likely to notice small errors or inconsistencies that others may overlook. They value accuracy and precision, which can make them excellent at tasks that require attention to detail, such as data analysis or quality control.

7. Traditional Values: ISTJs tend to have a strong sense of tradition and may value established norms and rules. They may be conservative in their beliefs and prefer to follow established procedures rather than embracing change or innovation. ISTJs often have a sense of duty and responsibility towards their family, community, or workplace.

8. Practicality: ISTJs are practical and pragmatic individuals. They prefer to focus on what is realistic and achievable rather than engaging in speculative or theoretical discussions. They are often skilled at finding practical solutions to problems and may have a talent for troubleshooting.

Remember that these descriptions are generalizations, and individuals may vary in their behavior and preferences. It's important to consider the context and observe a person's behavior over time to accurately determine their personality type.