Are Mexican immigrants less tidy than others?

The debate continues on Twitter about whether Hispanic immigrants tend to litter more.

On a related issue, General Social Survey interviewers rated the homes of respondents in terms of cleanliness from 'very clean' (1) to 'dirty' (5).  I calculated the means for those born in the US and those who were not (sample size = 7,062). The mean for native-borns is 1.96, the mean for immigrants is 1.86, so immigrants are not messier, they're cleaner.

What if we look by ethnic group and immigrant status? Let's limit the analysis to groups with at least 100 respondents. I'll put immigrant means in parentheses.

Mean unclean house score

Blacks 2.17  (2.02)
Mexican  2.00 (2.05)
Irish  1.98 (1.60)
Scottish  1.95 (1.89)
German  1.88 (1.68)
English/Welsh  1.84 (1.68)
Polish  1.84 (1.55)
Italian  1.77 (1.89)

Immigrants tend to be cleaner than native-borns. Mexican and Italian immigrants are the exceptions with slightly higher means than their American-born counterparts. On the question of Mexican immigrants, their score is only surpassed by blacks.

UPDATE: As I indicated, the debate actually focuses on Hispanics, not just Mexicans. The mean for all Hispanic immigrants is 1.90. For native-born Latinos, it's 2.03--a mean that is very close to that of Mex-Ams, and is only surpassed by blacks.