I have some of the cheap foam ones.
They attract turkeys just fine.
I've shot turkeys in my dekes for probably 7 years in a row.
The first turkeys I ever shot we used flat silhouette dekes.... again, they killed turkeys.
I'm no turkey expert, but between my son's and I we've killed maybe 45-50 in the last 10 years. All with cheap dekes.
I'm guessing 3/4 of a bird per hunter day.
I hope that helps.