The hose has a vacuum in it during operation, it's more likely to leak when the vehicle is sitting than running. If you clean the hose and it becomes greasy again, it likely has several pintip-sized leaks in it. You may have a leak in other places (like the gearbox or pump) but this is the easiest & cheapest part to do to rule out the cause. No filter in the pump I suppose could affect flow and cause issues as well, but not that frothing you're describing.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k