Founders put a lot of effort into raising money from the perfect mix of angels or raising a top tier series A. Unfortunately, a number of brand name investors will give you bad advice. Most of the time, this is out of a good natured attempt to help you. Occasionally, it is due to an investor trying to take advantage of you.
Startups often have email lists for their investors and advisors. I have now been on enough of these email threads to see brand name, top tier, investors inadvertently give terrible advice.
Examples may include:
1. Offers to make partnership introductions that are a waste of time.
As the entrepreneur it is up to you to screen and qualify what is a real opportunity and what to politely decline. One of the values of an investor may have a broad network they constantly offer to introduce you to. This can be quite helpful, but on your end you need to make sure to be judicious with your own time. Remember, you know your business better then anyone else and know who you should be talking to (and more importantly, who *not* to talk to).
If someone repeatedly makes blind intros, tell them to stop. These likely are wasting your time.
2. Product feedback.
If you are spending sufficient time with your customers, most investor product feedback will be high level and not super helpful. There are some people with an eye for product, or who have relevant experience that you can benefit from (e.g. running a growth team for a company successfully).
Others will give you canned advice to pursue the latest meme ("Can you make the images on your site ephemeral - you know, more like SnapChat?") or make suggestions that just don't make sense ("But why doesn't your dating site accept BitCoin?? Getting ahead of the curve on this one is strategic!").
3. VC intro mis-fires.
It is important during a fundraise that you get introduced to the right partner at any given venture firm.
Often, the person you get intro'd to first at a partnership takes the lead on representing you to the full venture partnership as well as takes the board seat if the firm invests. This means who you get intro'd to governs the fate of your company relative to the firm.
Many investors are not well networked to the full partnership at a VC, so will intro you to the wrong partner for your company.
4. Bad hiring suggestions.
One of my favorite all time investors tried to encourage my previous startup to hire someone they were friends with as our COO. We were only 6 people at the time, and did not have product/market fit. The COO candidate was a talented business person, but completely unnecessary for us at the time. The investor had given us lots of great advice on other topics in the past. He felt there was a "war for talent" and we should hire up while we could. This was pretty awful advice and would have been quite expensive (financially and more generally) if we had hired someone with a big salary and little to add at that stage of the company.
How to avoid bad advice?
Ultimately you asked these people to invest because you thought they could help you. As the founder, you need to take input from your investors but ultimately decide the right course or direction for your company. Remember, just because someone has a brand name doesn't mean they know what they are talking about.
The best entrepreneurs I know listen closely, seek multiple opinions on the same thing, and then decide for themselves. They question or point out underlying assumptions their advisors may have, and make sure the context of their own situation drives the solution.
There are also investors who are good at one thing but think they are great at another. E.g. someone with a broad network (supervaluable!) who thinks they also have good product advice (when they don't). Sometimes as a founder you need to just listen politely, nod your head, and then go get back to building an amazing product. You can always call your investor later when you need that key intro.
 Another post coming on this shortly.
 I am sure I have done so myself. If your advisors or investors are busy, they may pattern match rather then focus sufficiently on context. Sometimes pattern matching is sufficient, but the specifics of the situation obviously make a huge difference. The only good generic startup advice is that there is no good generic startup advice.
 With the exception, of course, of investor brand building :)
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