How might a customer demonstrate that they are losing their train of thought when intoxicated?

When a customer is intoxicated, one of the clear signs that they may be losing their train of thought is responding slowly to questions. This indicates that their cognitive processes, which include understanding and formulating responses, are impaired due to alcohol consumption. Slowed responses can suggest difficulty in focusing or processing information, which is a common effect of alcohol on the brain.

In contrast, speaking fluently would imply that the customer maintains coherence and clarity in their speech, which is often not the case when someone is drinking excessively. Making quick decisions does not typically suggest impairment; instead, it may indicate impulsiveness, which is another potential side effect of intoxication, but it doesn't directly correlate with losing one's train of thought. Asking many questions can occur for various reasons and doesn’t necessarily indicate cognitive impairment, as it may simply reflect curiosity or engagement in conversation. Therefore, the best indicator of a customer losing their train of thought while intoxicated is indeed their slow responses to questions.