Most golfers rarely follow the letter of all rules in casual friendly games. If you wanted to be a Nazi, you could find all kinds of minimal infractions. But who likes playing with Nazis?
If a hazard doesn't drain properly, then where should one cast the blame? If it was designed as sand, and not water, and the course fails to maintain it, then I think a free drop is entirely in order. When my group plays a certain golf course in winter, we know we will face this exact problem, and we stipulate a free drop to dry spots in those bunkers. It's our feeling that the game should be fun, and the course, equitable. To heck with the rules, in this case, until the course declares these bunkers to be water during winter (which would make more sense).
Otherwise, we follow the rules pretty much to the letter...at least, within friendly reason.
But, I might add that casual rules are another reason to count only tournament scores when calculating handicaps. We should do that.