Upon reading Mark Suster's post: "Why It's Critical to Reference Check Your VC", http://bit.ly/ifqKil, I pondered the fact that investments take a long time. Suster's article and links to his others go into how working with investors is a relationship building process that takes time. Here are some thoughts on this point.
The negotiations process can be taxing on the patience and sometimes, the emotions. VC's live in a world of contracts and attorneys so they are used to it. For entrepreneurs, the negotiation process can appear to be a profound lack of trust with a potential partner when everything leading up to this moment has been friendly. The point here is not to base your opinion of the relationship on the negotiation process. You are better off talking with others who have successfully survived a negotiation with this partner to find out about the relationship when everything gets back to normal. Plus, you should do it long before you jump into a negotiation. A good recommendation from another portfolio company will help you get through the process knowing it gets better at the end.
When checking references, ask questions that get to the "chemistry" of the relationship. We have seen cases where VC's are very active in the management of the company and others take a passive approach once the deal is done. Neither of these cases is either good or bad. You may benefit from expertise and contacts offered by an active investor or you may be better off with them on the sideline. That is up to you. The important thing is to find out how they operate post deal so you are not surprised.
Remember, an investor relationship will last the life of your company, or at least through an exit opportunity. It is easier to get out of a bad relationship with an employee than it will be with your funding partners so enter into the relationship with your eyes wide open.