I restored quite a few gassers this summer and dealt with my share of dirty plastic tables. I haven't tried most of the suggestions in this thread, but I'll put my technique up against any of em.
You need a tub/container big enough so you can submerge the plastic table. Fill tub/container with dawn soapy water (hot is best) and let it soak overnight. Following day take a scrubbie of some sorts and that gunk will come right off. Don't be shy with the Dawn either. It's cheap stuff and works amazingly well.