First of all, try not to focus on whether people are doing something just to be nice, or to avoid hurting your feelings. If it's a real and genuine compliment, then you're potentially dismissing it. If it's just a nicety, do you gain anything by knowing that? It should be a positive thing that someone is being nice or trying to avoid hurting your feelings.
If you want (or need) frank and honest feedback, then ask for it. You may not get it, but you're certainly more likely to than if you don't. You can help them to frame their response to, for example "Imagine I'm an author and you're my literary agent. Given that your success depends on mine, what would you change?" or even "what did you like least about it?"
As for the questions around descriptive writing, it's largely subjective. I know people who can't get into the Lord of the Rings because they feel Tolkien put too many words into The Shire, Bilbo's Party and general "hobbiting" before the fellowship even gets underway. Likewise, I have childrens' book authored by Bryce Courtenay, who is a fantastic writer - but in this particular book he gets bogged down in flowery metaphors that don't really add anything for the intended audience.
There's certainly nothing wrong with describing things in unambiguous terms. I prefer that style of writing for action scenes. It tends to keep the pace up, and if you have a lot of moving parts, it gives the reader more clarity. But I'd suggest that prior to getting into the action, unless it's a dramatic opening scene, you should try to give your reader a good sense of the actors and scenery before the action takes place. For example:
Bob charged, sending his assailant crashing through the flimsy market stall and onto the concrete floor.
That's quick and unambiguous. But well before Bob is attacked:
Bob had never seen anything quite like the city's night markets. A steady throng of people moved like the currents in a river; those in the middle could do nothing but float downstream, while off to the side little eddies would form as people broke off to barter with the hundreds of merchants and their eclectic wares. More often than not, the stalls were just as animated as the flow of people, with cages of sticks and twine holding all manner of livestock, from chickens that flapped a squawked to exotic, unclassifiable magical beasts.
I'd say that yes, it's possible to be overly descriptive, but that largely comes down to your intended audience and what they're likely to be interested in. If you're writing erotic fiction from a male POV, you'll probably spend significantly more time describing the physical attributes of the supporting characters than you will describing the lead. If you're writing a horror story where the main character is locked in a cell for the duration of the narrative, you'll spend more time describing their state of mind than their surroundings.
But you have to decide what's appropriate for your story. In the horror story example you might have a scene where your lead scours every inch of the cell looking for some way out, so you might have cause to go into great detail of something pretty mundane.
I don't know that anything I've written is actually helpful, but my sense would be that you're getting genuine positive feedback. Literature is broadly subjective, so I'd focus less on trying to establish a set of rules (beyond the incontrovertible stuff like grammar, etc) and find ways to get detailed, constructive feedback on work you have done.
