Dreamer by itself is not a bad thing but I presume you mean someone who is JUST a dreamer but doesn't seem like someone who would actually do the work to achieve those dreams ?
The best indication is their past actions. What have they done so far that gives you any indication they are worth partnering with. If nothing, I would definitely think twice.
Business is extremely hard. You need to partner with people who ideally have all of the below:
1. Perseverance. They understand that good things take time and need to constantly fight against odds to achieve success.
2. Dedication and focus. They are not all over the place. They only want to do this.
3. Relevant Skills/experience. You could be a first time business founder/partner BUT what skills do you bring to the table that are relevant in some ways to this partnership ?
This is well said. I have experienced same thing. They will talk lot about ideas but not try to understand what is happening under the hood and plainly ignore other's concerns instead taking them positively and thinking about it. They lie lot or just talk vague and escape when real problem comes.
I think the very premise of a startup is based on an idea of a dreamer. Otherwise the idea that give the startup a competitive advantage would have been taken already. The dream just has to be achievable and rooted in reality.
So maybe you are talking about someone who isn't rational, isn't reasonable, or are rigidly idealist (and not matching your/company ideals). Any signs of these qualities would be a warning. Stuff like the person not supporting their opinions with facts and insisting they are right could be a warning sign. Emotionally based opinions, business actions, or outbursts that are detrimental to the startup could be another.
I think dreamer in this context is the person who gets you fired up and giddy but you seem to be the person doing the work. Maybe irrational and emotional as you say. There is no malice but a lack of reality.
I haven't encountered this description of an off-base "idealist" founder, however during my time in SF I met many people like this.
Even those with impressive credentials, they seemed to jump from buzzword to buzzword starting something new every 6-8 months but never really committing or finding success.
Generally, I always avoid non-technical founders or first-time founders. Businesspeople who only have corporate experience and decide they want to "hire an engineer on the side" are should also be added to the "dreamer" definition IMO.
The best indication is their past actions. What have they done so far that gives you any indication they are worth partnering with. If nothing, I would definitely think twice.
Business is extremely hard. You need to partner with people who ideally have all of the below:
1. Perseverance. They understand that good things take time and need to constantly fight against odds to achieve success.
2. Dedication and focus. They are not all over the place. They only want to do this.
3. Relevant Skills/experience. You could be a first time business founder/partner BUT what skills do you bring to the table that are relevant in some ways to this partnership ?