3rd Party site suggestion

As a rule, is it acceptable to submit a site which I don't own (eg. one I've had a good experience with as a customer)?
... or can sites be submitted only by their owners?

I ask this because, whilst I may believe a site would be a useful addition to a category, I'd have no idea if the owner had already submitted it or not . If it turns out they had, I'd hate to send their site back to the start of the waiting list for review.

Anybody can suggest any website, no matter who owns it.

There isn't a queue; there's a a pool of websites awaiting evaluation in each category. An editor can process the pool in any order s/he wishes. When time is limited, I tend to cherry pick the ones with non-spammy descriptions first.

Thanks for that - especially your advice about descriptions.

However, it's been mentioned in a great many other threads that subsequent suggestions can overwrite the original suggestion, resulting in a delay - presumably if the editor was viewing the category pool in order of date. It's also been said that repeated suggestions can have a deleterious effect on a site being listed in any event.

I was concerned that, by making such a suggestion, I might bring this about - I'd really hate to harm a site's prospects. Your clarification of this is much appreciated.