Нет бы нам проверить номер этажа — мы приехали не туда.

not

Breakdown of Нет бы нам проверить номер этажа — мы приехали не туда.

• мы: we
• проверить: to check
• туда: there

Questions & Answers about Нет бы нам проверить номер этажа — мы приехали не туда.

What does нет бы mean here? It does not look like the usual meaning of нет.

Here нет бы is an idiomatic, conversational expression. It does not mean a literal no.

In this sentence, нет бы нам проверить номер этажа expresses regret, criticism, or annoyance about something that would have been sensible to do but was not done.

Depending on context, it can be translated as something like:

• we should have checked...
• if only we had checked...
• instead of that, we should have checked...

So the tone is roughly:
We should have checked the floor number — we ended up in the wrong place.

It often sounds mildly reproachful, either toward oneself or toward others.

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Why is бы used with an infinitive here? I thought бы usually goes with a past-tense form.