As a writer, you need to trust your editors and proofreaders, but you should still spend at least some amount of time polishing your writing before handing it over to them. Sure, this makes things somewhat easier for your proofreaders, but it also ensures clearer, better writing overall.
Do you have a clear review process that you follow before passing your work along to your proofreaders or editors? If not, here are a few things to consider if you want your writing to be the best it can be before giving it to someone else to edit.