Does a lower condo fee mean a well-managed condo?
NO.  A condo association may have low condo fees because it has no reserves for major repairs.  When it comes time to replace the roof, or repave the parking lot, or repair the heating system, the unit owners could have to come up with the entire amount on short notice.
But a higher monthly fee doesn't necessarily mean a well-managed condo.  The fee could be higher because other unit owners don't pay their fees on time, or because there have been major repairs, or because the condo trustees decided to increase reserves in anticipation of major repairs.
The amount of the condo fee isn't directly related to the health of the condo association, and there's no guarantee that the fees won't increase in the future.  Carefully reviewing the condo budget and financials will disclose more information.  Not every buyer's attorney reviews condo financials, so be sure to ask whether these important services are covered.  I always include condominium document review, including budgets and financials, when I represent condo buyers.