diff --git a/src/machines.jl b/src/machines.jl
index c251b22b..34364f98 100644
--- a/src/machines.jl
+++ b/src/machines.jl
@@ -93,9 +93,17 @@ warn_scitype(model::Supervised, X) =
     "input_scitype(model) = $(input_scitype(model))."
 
 warn_generic_scitype_mismatch(S, F) =
-    "The scitype of `args` in `machine(model, args...; kwargs)` "*
-    "does not match the scitype "*
-    "expected by model's `fit` method.\n"*
+    "The number and/or types of data arguments do not " *
+    "match what the specified model supports. Commonly, " *
+    "but non exclusively, supervised models are constructed " *
+    "using the syntax `machine(model, X, y)` or `machine(model, X, y, w)` " *
+    "while most other models with `machine(model, X)`. " *
+    "Here `X` are features, `y` a target, and `w` sample or class weights. " *
+    "In general, data in `machine(model, data...)` must satisfy " *
+    "`scitype(data) <: MLJ.fit_data_scitype(model)` unless the " *
+    "right-hand side is `Unknown`.  Here, the scitype of `args` " *
+    "in `machine(model, args...; kwargs)` does not match the scitype " *
+    "expected by model's `fit` method.\n" *
     "  provided: $S\n  expected by fit: $F"
 
 warn_scitype(model::Supervised, X, y) =
@@ -117,56 +125,6 @@ err_length_mismatch(model::Supervised) = DimensionMismatch(
 check(model::Any, args...; kwargs...) =
     throw(ArgumentError("Expected a `Model` instance, got $model. "))
 
-function check_supervised(model, full, args...)
-    nowarns = true
-
-    nargs = length(args)
-    nargs > 1 || throw(err_supervised_nargs())
-
-    full || return nowarns
-
-    X, y = args[1:2]
-
-    # checks on input type:
-    input_scitype(model) <: Unknown ||
-        elscitype(X) <: input_scitype(model) || begin
-            @warn warn_scitype(model, X)
-            nowarns=false
-        end
-
-    # checks on target type:
-    target_scitype(model) <: Unknown ||
-        elscitype(y) <: target_scitype(model) || begin
-            @warn warn_scitype(model, X, y)
-            nowarns=false
-        end
-
-    # checks on dimension matching:
-    scitype(X) == CallableReturning{Nothing} || nrows(X()) == nrows(y()) ||
-        throw(err_length_mismatch(model))
-
-    return nowarns
-
-end
-
-function check_unsupervised(model, full, args...)
-    nowarns = true
-
-    nargs = length(args)
-    nargs <= 1 || throw(err_unsupervised_nargs())
-
-    if full && nargs == 1
-        X = args[1]
-        # check input scitype
-        input_scitype(model) <: Unknown ||
-            elscitype(X) <: input_scitype(model) || begin
-                @warn warn_scitype(model, X)
-                nowarns=false
-            end
-    end
-    return nowarns
-end
-
 function check(model::Model, args...; full=false)
     nowarns = true
 
@@ -179,21 +137,13 @@ function check(model::Model, args...; full=false)
         @warn warn_generic_scitype_mismatch(S, F)
         nowarns = false
     end
-end
-
-function check(model::Union{Supervised, SupervisedAnnotator}, args... ; full = false)
-    check_supervised(model, full, args...)
-end
 
-function check(model::Unsupervised, args...; full=false)
-    check_unsupervised(model, full, args...)
-end
+    if length(args) > 1
+        X, y = args[1:2]
 
-function check(model::UnsupervisedAnnotator, args... ; full = false)
-    if length(args) <= 1
-        check_unsupervised(model, full, args...)
-    else
-        check_supervised(model, full, args...)
+        # checks on dimension matching:
+        scitype(X) == CallableReturning{Nothing} || nrows(X()) == nrows(y()) ||
+            throw(err_length_mismatch(model))
     end
 end