It is twaddle to say that you can only criticise a culture from within it. On the other hand you should not pre-judge people by reference to their colour race creed religion matrimonial statuus or sexuality.

There is however an unclear line between the practices that some cultures claim are religiously or culturally mandated (or permitted) but are properly to be objected to by the host culture, on the one hand, and those that are religiously or culturally mandated or preferred but although not preferred by the host culture are not properly to be prohibited.

Those properly to be objected to might without limitation include
clitorectomy
forced marriage
foot binding
the use of illegal drugs (Qat, or by Rastafarians, ganja - which I happen to think ought not to be illegal but is within the host state's competence to ban) or what about alcohol in the places it is banned?
Cruelty to animals
Child abuse (exorcism rituals, excessive punishment)
the carrying of practical cultural weapons (eg Kukri or Kris or Claymore)
Some clothing codes (eg the naked holy man, the bikini in the Vatican, the topless bather in Iraq!)
Non-notification of notifiable diseases
Excess occupancy (a health issue)
Noise nuisance
Other legal nuisance (public or private)
Planning permission and building regulations generally (but query the traveller communities)
Trespass


Two puzzlers are the Sikhs and crash helmets, and the Polish priests adn ther proposed zero tolerance breathaliser that will prevent priests travelling from communion). Another puzzler is the imposition of codes that might generally be seen as excessive - eg Islamic dress in Iran and Afghanistan. Should women be entitled to wear trousers in countries where that is not customary? What about polygamy/polygyny/polyandry?


Those which the host state might not like but should consider tolerating (with or without suggestion as to variation) could (without limitation) include
Cooking smells
Clothing customs that do not offend local decency laws (eg turban, fez, 3 piece man's suit in Bahrain)
Prayer habits
Ineffective weapons (the Sikh dagger, or the dirk)
Simple greetings (eg "Merry Christmas" which my stepdaughter was disciplined for saying to another Intel employee)
"Personal space" habits