“Do I look presentable?”
You're going to a formal dinner for an association that you're a member of. You have to dress up in a suit. After you get dressed, you want to know if you look OK, you ask your roommate like this.
Do I look presentable?
Looking "presentable" means looking good enough for people to see. In the example above, the speaker wants to know if he looks good enough for the event he's going to.
You can use this phrase to talk about people, as well as things like your home:
Let's start cleaning up a little. We want the house to look presentable when grandma comes over, don't we?
Or your work:
We should be able to make something that looks presentable by the end of next week.
Saying that something looks "presentable" suggests that it sometimes doesn't look good.
"Presentable" can also be replaced by "OK" in most of these examples:
Do I look OK?
We should be able to make something that looks OK by the end of the week.