I would never think someone who was speaking English as a second language and who made a mistake was not "up to standard."
When you hear native speakers saying things like "Where you at?" and "I seen it!" then anything an English learner says will sound like poetry.
I have tremendous respect for people who can communicate in more than one language.
Don't worry about the grammar. People will understand you even when you make a mistake with subject/verb agreement, or with articles, or with prepositions. Your goal is to get your meaning across, and you will.