Lack of cleaning does not often result in foam problems, except under the most extreme conditions. Generally lack of cleaning results in off flavors.
As long as you are following a line cleaning regimen, and running the cleaner through the coupler, you should be fine, you can always get a small brush and do mechanical cleaning as well, and while the low profile couplers don't disassemble and clean as easily as the traditional standard couplers, they can of course still be cleaned.