Banks, when they put up the money for you to purchase, are essentially partnering with you and sharing the risk of your investment. That is why it is difficult, if not impossible, to find a lender who is willing to gloss over any issues with the condo reserves. They will usually ask the buyer to put more money down to lower the bank's exposure, but sometimes will offer a higher interest rate in order to increase their reward for taking a larger risk.
I've run into situations like this before. My question is, "how big of an association are we talking about here?" With a 2-3-unit association (which Boston and the surrounding area are full of) you see this kind of thing all the time. I have come up with ways to work around it in the past.
If we're talking about a large association having little to nothing in reserve, it would warrant a closer look. Unless a larger association just finished a substantial capital improvement that sapped the reserve I would caution my buyer that an assessment is likely in the near future. If there has been a recent, large project, an underwriter will have some leeway to take that into account when they review the budget.
Best of luck!