This is my opinion for the Marin's from when I know them, early to mid 90's
Era is Early/Mid 90's
Everywhere sold them and typically cheap and entry level mountain bikes.
Bought in the thousands by middle aged people (aka your dad, uncle, fred down the road) who walk in to a bike shop wanting something costing a few hundred pounds to go riding on.
As proved by many people I know and my own dad with his Bear Valley SE 1995. Still stock since they day he bought it, entry level MTB bike used mainly for commuting and a hint of bridleways and hills. Designed well, works well and I like the ride it gives. It's comfy, well made, looks nice and cannot say anything against it. Perfect for the job it was bought for.
But because they where bought in large numbers by middle aged men with children and I was a teen, it is Un-Cool, especially if your Dad owns one.
Now I'm in that position, Father with kids it sounds like a perfect bike to buy, Comfy, Quality and doesn't cost a lot for what you get.
Which again makes them uncool
It's a Marin. Saying a Marin is cool, is like saying a Mondeo is cool.