Are things commonly blessed by priests at certain times of the year appropriate to bring to a priest for a special blessing?

Is it appropriate to ask priests to bless things like oil, salt and water that you bring to them for a blessing? I was reading [this answer](https://christianity.stackexchange.com/a/78215/4) and was wondering if it made sense for a layperson to bring things like salt and oil for a blessing. Would a priest be responsible for making sure that the thing they're blessing really _is_ salt, oil and water?