She will learn on May 16 whether she will be given a wildcard to play at the French Open, where she has twice been champion, which starts May 22.
Bouchard is the latest player to attack Sharapova, who the Canadian branded a "cheater" over her return having tested positive for meldonium at the 2016 Australian Open.
Bouchard said the Women's Tennis Association was sending the wrong message in allowing Sharapova to come back.
"She's a cheater and so to me, I don't think a cheater in any sport should be allowed to play that sport again," Bouchard, the world number 59, told TRT World in Istanbul where she had been playing a WTA event.
"It's so unfair to all the other players who do it the right way and are true. So I just think the WTA sends the wrong message to young kids: you know, cheat and we'll welcome you back with open arms." By reaching the quarter-finals in Stuttgart, Sharapova has already broken into the world's top 400 and is projected to rank 125th if she wins Sunday's final.
Despite the ongoing off court controversy, Sharapova is cutting an impressive figure on it.
Thursday's win was a far more polished, confident display from Sharapova, who hit nine aces and 29 winners against fellow Russian Makarova.
There was none of the rust or nerves she showed in beating Roberta Vinci 7-5, 6-3 in Wednesday's first round - the first day she was eligible to play after her ban.
But there is still work to be done as three-time champion Sharapova also had seven double faults and made 19 unforced errors "After yesterday's match it was tough to assess the quality of my level, because it was such an emotional match just to be back," she said.
"I was able to settle down today and get in more rallies.
"We had longer rallies, which was great for me because it gave me the chance to slide, then get back in position and do all the things you don't do when you don't compete." For a place in the semi-final, Sharapova will face Estonian qualifier Anett Kontaveit, ranked 73 in the world, who beat French Open champion and fifth-seed Garbine Muguruza of Spain.
"I haven't played her, she is one of the few girls on the tour I haven't faced yet," said Sharapova.
"She has been playing some great tennis here and this is a great opportunity for both of us."
The Russian says she is just relishing her return after so long on the sidelines.
"There is nothing like being at a tournament," said Sharapova. "I felt pretty good, the adrenaline and the challenge of each opponent is exciting.
"I'm already visualising the match before I play and it's a great feeling to have.
"You forget anything you feel in your body, despite not playing for 15 months." But she is facing constant questions about her doping ban and was terse when asked what lessons can be learnt by both her and the WTA.
"I am past 'the lessons', I have done numerous interviews about the case and this is a new chapter in my career and that's how I want to move forward," she said.
