Just as investors fire a long list of questions at startup teams (do they ever stop asking questions), founders can and should do the same with doting investors.

VCs have the benefit of being able to invest in numerous teams and themes, and thus diversify their capital such that failures don’t make or break their entire portfolio (side note: I’m starting a campaign to ban the word “portfolio” who’s in). Founders, on the other hand, are concentrating much of their personal capital into one asset: their startup. They can have much more to lose (but also more to gain).

Then why oh why don’t founding teams do more diligence on investors? You are about to get on a bus with a crew you better enjoy because it’s a long ride. Oh, and news flash: the road can (and will) get rather bumpy.

Founders may have checked off everything on their investor diligence list (meetings, phone calls, prior personal and firm investments, industry expertise, fit with team and firm, blog, Twitter feed, LinkedIn resume, etc.) but if they miss doing the reference check, they may end up with less than advertised. (I am focusing here directly on the partner of a firm not the firm’s reputation, as the partner with whom you will be working is more important than the firm.)

Founders will learn more about the information that comes out of a reference’s mouth than anything else about that investor. Not all the information will be glowing (especially the ones that fail), and sometimes people have differences of opinion, but on the whole a founding team will know what they’re getting after these calls are completed. The goal is to get an idea of how the investor delivered on his or her promises throughout all life stages of a startup.

Teams should first try to connect with as many investor references as possible before going to the investor. Scour an investor’s investments and connections to find people who know and have worked with him or her. Many times (hopefully) a startup will know many of these people, and if not, this may speak more to a founder’s lack of network than the investor’s.

Note: it is important to spend as much time doing the background check work before you go directly to the investor. When we at Promus Ventures go through the process of reference checks on founding teams, we have already talked to numerous people they have worked with in the past before we ask for additional personal references.

If I were a founder, and only after I could see myself giving this investor filling a coveted spot on my cap table (don’t waste their time or other’s if you’re not serious about them), I would ask this potential investor for the following reference checks:

1. Founder of company where investor participated and outcome was complete failure.

2. Founder of company where investor participated and outcome was complete success.

And if this investor is going to take a board seat, then I’d also add:

3. Founder of company where investor participated on the board (probably led the round as well so can understand that process as well).

An example: we recently finished the process of leading a round with a fantastic team that reference-checked us up and down. One of the co-founders knew three founders we had backed. The team talked several times with a vc (maybe more than one) that we had invested with on numerous occasions. I’m sure they talked to other folks that knew us as well. After these conversations, they then approached us and asked for three more references from founders in exactly each of the aforementioned situations.

Overkill? Nope — thoroughness. The team took their time to make all these calls because they understood the importance of the decision.

Final note: founders should recognize an investor is cashing in some of his chips by asking another busy founder to take time out of his or her schedule to talk. A team should find a way to be helpful to this person in some way rather than just getting on the phone and asking questions.

So don’t be afraid to ask a potential investor for references, regardless of who they are. Last thing you want is an investor that promised the world but delivered a goose egg. If a potential investor balks or grimaces at this ask, well, that will be an important tell in itself.