I'm not saying FIFA will allow a bad quality stadium to host the world cup, they surely have some standards and they will check the stadiums before every game also there is the same situation for hotels and training fields and FIFA should warn them if they see any bad quality stadium in any counting hosting the world cup, but still I"m sure you know the weather situation is much better in Canada comparing to Mexico and in the USA they have LA where there are many better hotels comparing Mexico.
Yes, in fact FIFA always makes reviews throughout the 4 years of construction of the World Cup and makes inspections with experts and they always keep their reports, in fact when things don't add up they are capable of taking away the venues, as happened in some sub 17 tournaments, now for the World Cup the demanding standards are higher, so the World Cup has to guarantee the highest quality in the stadiums and in the main soccer regulations, these things will always exist, I imagine that in every World Cup new things come up, and hosts have to meet those demands.