Listen - you have to take 'Shark Tank' with a little bit of 'Trumpiness'.
It's entertainment man.
The companies are chosen at least as much for their entertainment value as anything else.
Mark Cuban is not concerned about his 'reputation as a serious investor'. In fact, he's probably a joke in serious investment circles.
Mark is a 'pop culture' investor, he cultivates an image of what 'joe street' thinks a 'business investor' ought to be. Obviously - he is that to a great extent, he's putting real money on the line, but he's not a VC in the the more orthodox sense.
He'll have his team do due diligence after the fact, and do a no/go later on.
All of the ridiculous fights, 'isms' and 'sayings' etc. - they are like 'Trump tweets' - you think it will damage him, it won't. It's pop culture ... where having the eye-balls matter. He has legions of 'at home followers' who look up to him. That's his audience.
He might lose an inch of cred with people like you and I, but gain at least as much back from of the kinds of people that watch this show.
I've never looked into the details, but I imagine the paperwork Shark Tank entrepreneurs sign includes something along the lines of "all deals agreed are non-binding and subject to completion of satisfactory post-show diligence blah blah". I'd be shocked if a decent percentage of the deals featured don't ultimately fall through for one reason or another at the diligence stage with zero impact on the investor's reputation, so I don't think Cuban will lose too much sleep over it.
Edit: From this AMA on reddit with Mark Cuban 3 years ago, he says that about 25% of deals have something wrong (and therefore presumably don't work out).
https://www.reddit.com/r/IAmA/comments/15doqt/mark_cuban_thi...
If I was Mark Cuban, I'd be fucking livid at the production for not seeing the risks of doing due diligence at his own expense, both intangible and tangible costs.