At the time there was substantial anti-Chinese sentiment in the United States, e.g., as reflected in the Chinese Exclusion Act of the late 19th Century.
During that time they visited 251 hotels and restaurants and, while LaPiere reports that some people greeting them looked curious, they were turned away only once.
LaPiere concludes that positive reactions were associated with factors unrelated to the race of the couple (such as neat appearance and smiling).
Six months after the conclusion of their travels (to provide a chance to forget their behavior), LaPiere mailed a survey to all of the businesses they visited with the question, "Will you accept members of the Chinese race in your establishment?"
[1] The Department of Sociology at Stanford University's annual research award for best graduate student paper is named in LaPiere's honor.