The most annoying investors are those who do not value the founders' time.

Investors must maintain their own reputation and should not lack the professionalism expected of them as buyers. Recently, during a gathering with friends in the Bay Area, three types of funds were particularly criticized.
One type is the "always learning type" who says they want to invest but doesn't even bother to look at the deck beforehand. They don't understand the basic knowledge of the industry at all, have never heard of any leading players or star projects in the industry, haven't used or researched any products, and don't understand the business models within the industry. They treat the project's sharing as a free expert call, and even listen to it like a podcast.
The second category is "We will sign and make the payment next week". After giving a verbal investment commitment, materials are required every week and the team is asked to meet across continents, countries, and cities every month. However, the due diligence time for pre-seed takes three to five months. I even heard the most bizarre case today where they said they would invest from the pre-seed stage but only followed up after internal discussions until the project completed the seed and Series A rounds. Don't be ambiguous; just be straightforward.
The third category is the most excessive, which involves asking about technology, suppliers, channels, and client lists under the guise of confidentiality. They ask questions without limits and obtain sensitive materials and information in the name of due diligence, only to turn around and sell the project’s suppliers, client lists, and technical implementation methods as favors to competitors or their portfolio. In 2022, I even encountered a fund that directly gave our unreleased Figma designs to their portfolio for pixel-level copying.
To be honest, it takes time to learn, it takes time to reach internal consensus, and it is understandable and cooperative to understand more details, but investors must clarify their own positions. At least be nice people and be helpful.