A blue coin is near the start point. Go straight and there is a standing block in front of you. Squirt it from the other side, and there's a blue coin!
Before you enter the hotel, spray the fires surrounding the hotel and one of them should have a blue coin.
All 30
1)Underwater off the coast of the beach (all episodes).
2)Spray the sign overlooking the sunset (all episodes).
3)Spray the second torch from the left in front of the hotel (all episodes).
4)Clean the M Graffiti by the hotel (episodes 7 and 8).
5)Water the sunflower garden beside the hotel (episodes 2 thru 8).
6)Underneath a hut (episodes 2 thru 8)
7)Outside the hotel on the back of the second floor (episodes 2 thru 8).
8)(Now inside) Corresponding Triangle marks [floors 1 and 2] (episode 7 and 8).
9)Same as above (episode 7 and 8).
10)Corresponding X marks [1F and 2F] (episode 7 and 8).
11)Same as above (episode 7 and 8)
12)Spray the skylight [3F] (episodes 3,4,5,7,8)
13)M Graffiti [3F] (episodes 7 and 8).
14)Spray the lamp [3F] (episodes 3,4,5,7,8)
15)In the room behind the Boo poster [Attic to 3F] (episodes 3,4,5,7,8)
16)Go back to the room, and spray the empty bookcase [3F] (episodes 3,4,5,7,8).
17)From there, Ground Pound the different colored tile [3F to 2F] (episodes 3,4,5,7,8)
18)Smash the box in the next room [2F] (episodes 3,4,5,7,8)
19)Defeat the Boo [Attic] (episodes 4,5,7,8)
20)Go to the middle of the Attic and spray the M graffiti [Attic] (episodes 7 and 8)
21)In the air duct [Attic] (episodes 3,4,5,7,8).
22)From the Attic, find the room with the mirror and spray the mirror [Attic to 3F] (episodes 3,4,5,7,8)
23)From there, Ground Pound the table for to find a blue coin [3F to 2F] (episodes 3,4,5,7,8)
24)(Back outside) Wash the two Nokis (episode 6)
25)Same as above (episode 6)
26)(Inside) M Graffiti above the door [Casino] (episode 5)
27)Ground Pound the slot machines [Casino] (episodes 4 and 5)
28)Put out the torch [Casino] (episode 4 and 5).
29)Clean the Nokis (outside) (episode 6)
30)Same as above. (episode 6).